Free Shipping & Free Returns*

FREE SHIPPING on Over 250,000 Products

Shop now and get Free Value Shipping on most orders over $49 to the contiguous 48 states, DC, and to all U.S. Military APO/FPO/DPO addresses.

Enjoy our FREE RETURNS

We want to ensure that making a return is as easy and hassle-free as possible! If for any reason you are not satisfied with your purchase, simply return the item within 30 days of receipt, and we'll cover the cost of return shipping. Learn more about our Return Policy.

Shopping Cart
Monstrum Flip-Up Lens Cap Set for 1x20mm Red Dot Sights
Currently Unavailable View Product
Compare (0)
Most Helpful Negative Review hard to install
It works but its hard to install. The internal diameter is small, i had to put it in boiling water first so its expand. If you didnt do this, you probably wont be able to install it. One good thing would be that its real tight once you get it on. No chance it'll come off alright.
Show
Sort by
Filter by

Great product!

by REN, Verified Owner from TX, United States Written on March 22, 2025
It’s an excellent upgrade if you’re expecting dust or rain. Had to warm them up a little to fit on a Holosun, but a tight fit is good.
Would recommend: Yes
Was it helpful to you? Yes | No

Decent but not perfect

by Frank, Verified Owner from WA, United States Written on July 20, 2023
These fit the Sig Romeo 5 with the cr2032 coin battery. There’s not much lip to grab onto on a Romeo 5, so they do ok for what they are. I got one set that was softer plastic and one set that was harder plastic. Not sure why. The harder plastic set stays on much better. The softer ones tend to fall off. A little dab on super glue took care of it.
Would recommend: Yes
1 of 1 found the following review helpful.
Was it helpful to you? Yes | No

Not universal

by Smitttydog, Verified Owner from MA, United States Written on August 22, 2022
These are not universal. I bought these for my Sig Romero 5. And because the battery nipple is right below the front lens you can get a cap on. Impossible. Fit no problem on my Vortex red dot and it’s a nice flip function but not happy they don’t fit on the set up I wanted.
Pros:
  • None
Cons:
  • not universal
Would recommend: Yes
1 of 1 found the following review helpful.
Was it helpful to you? Yes | No
There are no reviews that match your criteria. Would you like to review this product?
Last updated 2025-11-12 UTC.