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Master Lock

Master Lock 8170D, 6-1/8 inch Wide U-Lock with 8" Shackle, Black

Based on 5,113 reviews
Condition: New
Product info up-to-date
$18.98
Save $0.56 was $19.54

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This item's return window has been extended for the holiday season: FREE refund/replacement until Jan 31, 2027

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Availability: In Stock.
Fulfilled by Amazon
Arrives Wednesday, Nov 4
Order within 23 hours and 13 minutes

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At a glance

Condition
New
Style
No Cable
Size
6-1/8 in U-Lock
Model
8170D
Dimensions
9.8 x 7.33 x 1.33 in
Weight
2 lb
Color
Black
In the box
U-lock bike locktwo keysand a carrier bracket

Features 5

  • Outdoor heavy duty bike U-lock is best used as a bicycle lock.Note: Measure your door's backset, cross bore and thickness to ensure you find the right fit.
  • U-shaped steel bike lock with key; Includes carrier bracket for easy transportation
  • Bike lock features a hardened steel body and double locking shackle for superior cutting and prying resistance
  • Bike lock body is 6-1/8 in. (16 cm) wide, with 8 in. (20 cm) shackle length, 4 in. (10 cm) width and 1/2 in. (13 mm) diameter

Description

The Master Lock U-Lock is engineered for those who value their ride. This bicycle lock offers unparalleled security to ensure your bike stays right where you left it. It is crafted from hardened steel that can withstand significant impacts and resist all manner of attempts at tampering or cutting. This makes it an exceptional choice among bike locks for anyone serious about anti-theft security. The bike lock body is 6-1/8-inches wide with an 8-inch shackle length. Whether you are locking up your bicycle in a bustling urban environment or a quieter suburban area, trust that this heavy-duty bike lock has you covered. Its imposing presence alone deters would-be thieves before they even think about attempting anything nefarious. But what sets this U-lock bike apart from others? The answer lies in its intuitive design and ease of use. Despite its strength and durability, the Master Lock 8170D U-Lock is incredibly user-friendly. It boasts a double-locking mechanism providing twice the security while ensuring quick access when you need to unlock it swiftly. Lightweight yet sturdy, this U-lock fits easily into most backpacks or bike accessory bags without weighing you down. Investing in the Master Lock U-Lock means investing in long-term security for your precious ride. Unlock superior protection now with Master Lock: where studied design meets impenetrable strength.

Specs 30

Brand Master Lock
Special Feature Heavy Duty
Lock Type Key Lock
Item dimensions L x W x H 9.8 x 7.33 x 1.33 inches
Material Alloy Steel, Rubber
Brand Name Master Lock
Recommended Uses For Product Bike
Number of Pieces 1

Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Wednesday, Nov 4

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.

  • Klarna Financing
  • Affirm Pay in 4
  • Affirm Financing
  • Afterpay Financing
  • Zip Pay in 4
  • Financing through Apple Pay
  • Financing through Google Pay
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

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Top Amazon Reviews

Good lock
Style: No Cable Size: 7-1/4 inch U-Lock
Feels solid and works well. Easy to use and keeps my scooter secure.Great buy for the price
Reviewed in the United States on September 24, 2026 by Soph B
Strong, Secure, and Useful for More Than Just Bikes
Style: No Cable Size: 7-1/4 inch U-Lock
Review Image by Jenny’s Cozy Corner
I originally chose this U-lock for a bicycle, but I ended up using it to secure the door on our outdoor shed, and it has worked extremely well. The lock feels very sturdy and well made. It’s easy to lock and unlock with the included keys, and the solid construction gives me confidence that it’s helping keep our belongings secure. I also appreciate that the protective coating helps prevent scratches. Even though it’s marketed as a bike lock, I found it to be a versatile security lock that works well for other outdoor applications too. If you need a dependable lock for a bicycle, shed, gate, or similar item, this is a great option. Overall, it’s a quality Master Lock product that’s simple to use, durable, and provides excellent peace of mind. ... show more
Reviewed in the United States on June 26, 2026 by Jenny’s Cozy Corner
Well made
Style: No Cable Size: 7-1/4 inch U-Lock
Master keys are high quality and well made, affording price.
Reviewed in the United States on September 10, 2026 by VV
Gets the job done well
Style: No Cable Size: 7-1/4 inch U-Lock
For the price the lock itself is obviously very sturdy and will definitely get the job done. The star docked off is for the holder; it's plastic with a piece of rubber then screwed together to keep it secure, but every time I have a holder like that, it inevitably begins to slip from its place. I don't tend to use the holder in the first place, so this isn't much of an issue for me, but it's something to be considered. It can also be a bit annoying to lock and unlock just because you have to put both ends in at the same time with the lock fully unlocked, and if you are bending down or doing it at an angle, it can be a struggle to get it just right. But this doesn't really affect the quality or security of the lock itself once it's on. ... show more
Reviewed in the United States on July 7, 2026 by Felix
A good deal; I'd buy them again!
Style: No Cable Size: 7-1/4 inch U-Lock
The deal I had on Amazon was hard to pass on, and I've been looking at this product for a while. Point, click, wait... they arrived in a sturdy box, in impeccable condition. One word of warning... the key releases the bar completely from the horseshoe section, so it will drop off once it is disengaged. No regrets; I'd buy them again ... show more
Reviewed in the United States on July 15, 2026 by o2btravling
Good value, annoying lock
Style: No Cable Size: 7-1/4 inch U-Lock
Feels like a solid lock. I use it to lock up my electric scooter for typically 15 minutes to an hour at a time while I go into the grocery store or for appointments. Otherwise the scooter is in my garage or office. With this lock, I don't worry at all about my scooter being stolen. It is however annoyingly difficult to get it locked up again after unlocking it. I thought it would just snap back in, but the key has to be in and turned the correct way for it to go back in, so it takes some getting used to. Overall, it keeps my scooter secure and was a great price. ... show more
Reviewed in the United States on September 23, 2026 by Marco
Dependable bike lock
Style: No Cable Size: 7-1/4 inch U-Lock
Works great, easy to use, sturdy quality! Master lock is a trusted brand to keep my bike secure.
Reviewed in the United States on September 16, 2026 by Jewells
Nice lock
Style: No Cable Size: 7-1/4 inch U-Lock
Nice lock for me
Reviewed in the United States on August 25, 2026 by Yuhaoyeh
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