Search  for anything...
Couldn't find selected product
Monstrum

Monstrum Guardian 3-9x Rifle Scope with Illuminated MOA Reticle

  • Based on 137 reviews
Condition: New
Checking for the best price...
$59.99 Why this price?
Holiday Deal · 65% off was $169.99

Buy Now, Pay Later

As low as $10.00 / mo
  • – 6-month term
  • – No impact on credit
  • – Instant approval decision
  • – Secure and straightforward checkout

Ready to go? Add this product to your cart and select a plan during checkout.

Payment plans are offered through our trusted finance partners Klarna, Affirm, Afterpay, Apple Pay, and PayTomorrow. No-credit-needed leasing options through Acima may also be available at checkout.

Learn more about financing & leasing here.

Selected Option

Free shipping on this product
This item's return window has been extended for the holiday season: FREE refund/replacement until Jan 31, 2026

To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

Availability: In Stock.
Fulfilled by Amazon
Arrives Tuesday, Dec 23
Order within 1 hour and 47 minutes
Available payment plans shown during checkout
Protection Plan Protect Your Purchase
Checking for protection plans...

Recently Viewed

Style: Black | 3-9x40


Features

  • Adjustable 3-9 times magnification, for targeting out to 600 yards and beyond
  • Fully illuminated MOA reticle with MOA hashmarks for ranging information and inline dial controlled brightness adjustments
  • Aircraft grade 6061 aluminum scope body with a sealed, nitrogen-charged tube for resistance to water and fog
  • Precision 1/4 MOA/click windage and elevation adjustments
  • Package includes Medium Profile Picatinny/Weaver Scope Rings and set of flip-up lens covers

Description

The Monstrum Guardian Series is the latest iteration from our best selling line of SFP rifle scopes! The scope comes equipped with: Adjustable 3-9 times magnification, for targeting out to 600 yards and beyond Fully illuminated MOA reticle with MOA hashmarks for ranging information and inline dial controlled brightness adjustments Precision 1/4 MOA/click windage and elevation adjustments Anodized aircraft grade 6061 aluminum construction, for lightweight and durable performance An integrated throw lever for smooth and controlled adjustment of the magnification dial A sealed, nitrogen charged scope tube for resistance to fog and water The Guardian 3-9x weighs 15 ounces. It has a 1 inch diameter tube and requires a mount with 1 inch diameter scope rings. The scope is 12 inches in total length. Package includes: A set of medium profile scope rings compatible with all Picatinny or Weaver mounting platforms. A set of flip up lens covers One CR2032 battery

Brand: Monstrum


Color: Black


Style: Black | 3-9x40


Sport: Hunting


Item Weight: 15 Ounces


Material: Aluminum


Magnification Maximum: 9 x


Objective Lens Diameter: 40 Millimeters


Magnification Minimum: 3 x


Compatible Devices: Rifle


Brand: ‎Monstrum


Color: ‎Black


Style: ‎Black | 3-9x40


Sport: ‎Hunting


Item Weight: ‎15 Ounces


Material: ‎Aluminum


Magnification Maximum: ‎9 x


Objective Lens Diameter: ‎40 Millimeters


Magnification Minimum: ‎3 x


Compatible Devices: ‎Rifle


Mounting Type: ‎Weaver Mount


Night vision: ‎No


Field Of View: ‎38.7 Feet


Model Name: ‎SG3940-B


Manufacturer: ‎Monstrum


Reticle Type: ‎MOA Crosshair


UPC: ‎810088810787


Item Package Dimensions L x W x H: ‎16 x 3.55 x 2.95 inches


Package Weight: ‎0.75 Kilograms


Brand Name: ‎Monstrum


Part Number: ‎SG3940-B


Date First Available: June 27, 2022


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Tuesday, Dec 23

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
  • PayTomorrow Financing
  • Financing through Apple Pay
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

Similar Products

Top Amazon Reviews

    • Good bang for the buck
Style: Black | 3-9x40
Monstrum is frequently criticized on various forums for its low cost, leading many to advise against purchasing it. However, I believe many of these individuals have never actually used the scope. I had a Ruger 10/22 from the early 90's which had a Tasco 4x20 on it and it had yellowed throughout the years; I could hardly see through it. Since the gun was a 22 I decided to give Monstrum a try. I picked up the scope and rings for 49.99 plus tax. I am impressed that it is a 3-9x40 scope and the reticle lights up green or red. This also has .25 MOA adjustments. I mounted this on the gun and had no problem zeroing the gun. It was dead on at 25 yards. Also the optic was decently sharp. Monstrum does offer a life time warranty and I signed up for this through their website. I think this is a decent scope for a 22 or any other budget rifle. I would not recommend this scope for a mid range or higher end rifle build. For instance an equivalent Vortex entry level scope will cost about 150 and rings will be around 50 so you would pay 200 dollars. ... show more
Reviewed in the United States on July 4, 2025 by Kevin
    • A Real Bargain
Style: Black | 3-9x40
Excellent quality and performance at a very fair price. Works great on my 7.62x39 AR15.
Reviewed in the United States on June 5, 2025 by Superkicker
    • Decent enough for pcp airguns or rimfire rifles
Style: Black | 3-9x40
For the price, the scope performs as it needs to. The magnification at 9x doesn't really seem like it zooms in that much, the clarity is decent, but again, it's a budget scope. It has worked just fine on my PCP air rifle, sighted in without an issue, but not sure if it would hold up to a spring or gas ram style of airgun. The reticle is decent, but it could have been better defined on the "mil dot" aspect of it. Hard to use them properly because they're not crisp, clear dots as in some more expensive scopes. The scope is not a bad deal, but keep your expectations realistic when buying a budget scope 🤷 ... show more
Reviewed in the United States on February 21, 2023 by Joe
    • Good scope
Style: Black | 3-9x40
For the price it’s not bad I love that it have the resettable Tourette’s but kind feel the magnification kinda week set it up on a 10/22 lvt it’s my sub sonic semi auto set up so I don’t shoot it much past 50 yards it’s a hunting set up but with the resettable Tourette’s I can adjust it out to 100 yards in with the flip up scope caps I’ve got the settings for 75 and 100 written in the camp I’m a big fan of the monstrum scope I run several of there ffp on my match rifles n they are always in the top 3 I even with guys running nightforce and other high end scopes ... show more
Reviewed in the United States on May 25, 2025 by adam
    • Worth the money
Style: Black | 3-9x40
Better than some much more expensive.
Reviewed in the United States on July 21, 2025 by Robert K. Kilpatrick
    • Inexpensive scope.
Style: Black | 3-9x40
Was about what I thought for a inexpensive scope it sighed in fairly quick, not as clear as I would like, the cross hairs are not well defined. Now to see it it will last on my 300 BLK. I do like the choice of red or green illumination.
Reviewed in the United States on November 28, 2025 by PRZ
    • 10/10
Style: Black | 3-9x40
Incredible, eye relief is great, clarity is great, every thing is great!
Reviewed in the United States on September 10, 2025 by Nick D
    • Great Scope
Style: Black | 3-9x40
Excellent scope the lens is clear as any scope that cost 4x
Reviewed in the United States on July 21, 2025 by Jimmy Carter

Can't find a product?

Find it on Amazon first, then paste the link below.
Checking for best price...