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G-Shock

Casio GA-B2100-1A1JF [G-Shock GA-B2100 Series Men's Rubber Band] Watch Shipped from Japan Released in Apr 2022

  • Based on 586 reviews
Condition: New
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Availability: Only 5 left in stock, order soon!
Fulfilled by Amazon
Arrives Jul 24 โ€“ Jul 29
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Description

Introducing the sleek and robust Casio GA-B2100-1A1JF, a modern take on the classic G-Shock design. This unisex watch boasts a 45.4mm x 11.9mm carbon/resin case, housing a solar-powered quartz movement with a battery life that's virtually maintenance-free. The GA-B2100-1A1JF is equipped with Casio's Tough Solar technology, ensuring it stays powered even in low light conditions. The watch features a 200-meter water resistance rating, making it suitable for swimming and snorkeling, while its shock-resistant structure provides durability for everyday wear. The GA-B2100-1A1JF also comes with Smartphone Link functionality, allowing you to connect to your smartphone via Bluetooth to receive time calibration and other useful features. The watch's modern, octagonal design is accentuated by a black resin band with a buckle closure, making it a stylish and practical choice for both men and women.

Package Dimensions โ€ : โ€Ž 4.41 x 3.58 x 2.52 inches; 1.83 ounces


Item model number โ€ : โ€Ž GA-B2100-1A1JF


Department โ€ : โ€Ž mens


Batteries โ€ : โ€Ž 1 Lithium Ion batteries required. (included)


Date First Available โ€ : โ€Ž May 13, 2022


Manufacturer โ€ : โ€Ž Casio


Product Warranty: For warranty information about this product, please click here


Best Sellers Rank: #21,659 in Cell Phones & Accessories (See Top 100 in Cell Phones & Accessories) #2,249 in Smartwatch Bands


#2,249 in Smartwatch Bands:


Display: Analog-Digital


Watch Movement Type: Quartz


Additional Features: Shock Resistant


Power Source: Solar Powered


Strap Type: Two Piece Strap


Water Resistance Depth: 200 Meters


Sport Type: Walking


Clasp Type: Buckle


Water Resistance Level: Water Resistant


Embellishment Feature: Crystal


Closure Type: Buckle


Style Name: Modern


Band Color: Black


Dial Color: Black


Theme: Sports


Face Style: Modern


Brand Name: G-Shock


Model Name: GA-B2100-1A1JF


Model Number: GA-B2100-1A1JF


Series Number: 2100


Item Weight: 52 Grams


Global Trade Identification Number: 46


Manufacturer: Casio


Manufacturer Part Number: GA-B2100-1A1JF


Unit Count: 1 Count


Band Material Type: Resin


Case Material Type: Carbon/Resin


Crystal: Glass


Case Diameter: 45.4 Millimeters


Band Width: 26.1 Millimeters


Case Thickness: 11.9 Millimeters


Band Length: 20.5 Centimeters


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Jul 24 โ€“ Jul 29

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Top Amazon Reviews

    • Casio makes Great Watches
At first the wrist strap was extremely tight around my large wrists. However after the months of use and breaking in the strap it seems to be more comfortable. It's a great watch Bluetooth tough solar. Nice back light to read time. Minute hand moves exactly on the second. Display obviously is dark. If you want the digital to be more legible don't get the negative display. Overall it's a great time piece, Casio knows how to make watches. I've noticed the Battery level go from High to medium and it show the battery level in the Casio app with the Bluetooth and it even has a phone finder feature which is nice but I don't usually use the app everyday just when I need to update the device. It's a g-shock they are great time pieces. Definitely worth it and I recommend their Multi Band 6 watches if you live close to one. I got the 5610 U also and have been enjoying that one also, charge them at full at the same time and that one has not moved from high battery level. ... show more
Reviewed in the United States on August 21, 2025 by Blue Garcia
    • Night OPS
Love to watch if you like a blackout watch's this one is it. Not impressed with the band feels and looks cheap, I doubt the buckle will last long with me. I plan on replacing the band with an upgrade mod kit.
Reviewed in the United States on January 17, 2026 by Cactus Ren
    • Some surprises, but better than I was expecting
Edit: Well, I tried, but this watch isn't working for my daily wear. I still give it 5 stars and I am keeping it because it has a classy look and is still very usable. My problem is that I cannot see the negative display without glasses and a lot of light. I'll be getting the GA-B2100-1A for daily wear, and reserve this one for a night out on the town. This is a "first impressions" review. I'll try to update it later. I'm a 58y/o man, 6'2, 240#, so not "skinny" wrists, and my eyes aren't as good as they used to be. I say that to explain why I wanted to give this a 4 star review, but have to give it a 5 because the issues are not with the watch. I've worn a Timex Katmai combo Expedition watch for years, and remember G-Shocks as being bricks held on with ratchet straps. This one is surprisingly light, and where the Timex with the canvas strap needed to be adjusted several times throughout the day as my wrists expanded or contract, the band on this G-Shock has enough give that I haven't needed to touch it, or even think about it while I've been wearing it. I wanted the blacked out, or stealth, variant, and while I was surprised by what I got, it is what I ordered (mostly...more on that later). It is shades of black or dark grey, and very unassuming. The hands are photo luminescent (need to be charged with a flashlight, and fade quickly), and their uncharged color is a light- to medium-grey. No other parts of the watch face are luminescent, but all can be reasonably well seen when the light button is pressed. The LCD is a negative display, so the "background" is black, and the letters and numbers in the display are "not black" (not quite white, so maybe a light grey). Although the display is a little difficult for me to read "quickly", my light meter says that I'm in 8 lux of light, so any difficulties that I'm experiencing are like due to my eyes and my environment. However, when I move to a brighter setting (68 lux) the analog hands are easily read, and the LCD only takes a moment longer to read. (The feature to quckly and easily move the hands out of the way of the other displays is a very nice and welcome touch!) Also, between the reflective face of the watch, and the highly polished crystal, it does take a second to find an angle off of the light where I can read the dials and displays. The watch arrived with the battery at half-charge (indicator pointing to "M"), but from the research I've done this won't be a problem, and assuming I spend the majority of the weekend outside I should have a full charge before too long. I would note that this product is the "JF", and while the box I received says "JF", the tag on the watch is "ER". This doesn't seem to have made any difference in the functionality, and after watching other un-boxing videos I do think this was opened and repackaged (although there is no sign of wear and tear on the watch, can, box, or documentation). The blue-tooth app for my phone made this watch easy to configure, which was a real joy because I was dreading setting everything up on the watch itself. The two recommendations I would have for Casio would be to ( 1 ) black out the control buttons and screws on the sides of the case (the buckle is a strong plastic instead of shiny steel, it would be good if the buttons were too), and ( 2 ), even though this is a stealth model, make the hands a little more visible with either a true white luminescent paint, or just white and let the onboard light be used in no-light conditions. Overall, I do highly recommend this watch for daily wear given it's durability, usability, and capabilities. ... show more
Reviewed in the United States on September 15, 2023 by Chuck B
    • Hands Down My Favorite All Around Watch!
I purchased this watch as a sort of Birthday gift to myself and it was even nicer in person! Itโ€™s not even close to the most expensive watch that I own and yet I find myself wearing it almost every day! In fact, it became my go-to wear for vacations as well and with the cellphone bluetooth app connectivity feature I even programmed event reminders that come up on the watch directly which was awesome and a feature I didnโ€™t know it had. Sure the screen is a bit small at times to read those messages but itโ€™s still a cool option which I enjoy. If you can afford it, spend the little extra for this bluetooth version of the watch but if not then no worries the version with less features still looks identical! ... show more
Reviewed in the United States on November 11, 2025 by Amazon Customer
    • GShock quality + Solar! Never needs a new battery
Review Image by Joe
Review Image by Joe
Review Image by Joe
Review Image by Joe
The media could not be loaded. My favorite watch. Love the sleek black on black with grey accents and negative digital display. Love the solar aspect, I'll never need to change battery, so long as wear the watch somewhat regularly, or put it near a window a couple days every few months. Been a watch lover since I was a kid, but never really wore them for many reasons. Don't know why I ever overlooked the casioak style GA/GA-B 2100 models. Love them, and they're great quality. ... show more
Reviewed in the United States on June 6, 2025 by Joe
    • Read My Review.
Review Image by Dyl
Okay so after doing weeks of research, i decided to buy this watch, i was hesitant to buy it off of Amazon after seeing tons of videos about fakes. I just received this watch 5 days earlier than expected. Ive done all the checks, iโ€™ve closely scrutinised every single thing about the watch, the fonts, the light, the watch face. If youโ€™re worried about this watch being a fake, DONT. This is a genuine Casio G-Shock B2100-1A1. The title of the post says JR, which simply means it was a Japanese manufactured watch. If youโ€™re on the fence about making the purchase, i was too, and im super happy. The face is Blacked out, if youre into blacked out watches/ products, you hopefully understand that it would be less visible, i have no problem with this, the peoples reviews about not being able to see the watch, SHOULDNT HAVE PURCHASED THIS COLOUR VARIANT. Also after doing tons of research, this Amazon sellers price on this watch is extremely good, i live in SA, and if i wanted to buy it from a store i would pay 30% more than buying and shipping it from this seller. I have a 6-7 inch wrist width and it looks exactly like how i was hoping. Thanks to the seller! ... show more
Reviewed in the United States on August 12, 2024 by Dyl

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