Monstrum Rubberized Flip-Up Rifle Scope Lens Review
It’s a classic scenario: you’ve spent good money on a rifle scope, and then you realize the lenses are just sitting there, collecting dust, getting scratched from brush, or fogging up in your hunting pack. You want something simple, affordable, and reliable to cover them. That’s exactly where the Monstrum Rubberized Flip-Up Rifle Scope Lens Covers come in.
After digging through hundreds of verified buyer reviews, comparing specs, and looking at how these hold up against the competition, the answer is clear: these covers are a fantastic value for anyone who wants basic protection without overthinking it. They’re not the toughest or most waterproof option out there, but they cost a fraction of what premium brands charge. Let’s walk through why they might be the right pick for your next range trip or hunt.
What it is
Flip-up scope covers, sometimes called bikini covers or lens protectors, are a simple way to shield your rifle scope’s glass from dust, mud, and scratches when you’re not aiming. The Monstrum version is a rubberized, one-piece design that snaps over the objective and eyepiece. It uses a spring-loaded hinge so you can flip it open with a thumb tab and shoot without removing it.
This model positions itself as a budget-friendly alternative to brands like Butler Creek or Vortex, offering similar functionality at a fraction of the price. It’s made for hunters and range shooters who want basic protection without spending a lot.
Setup & first impressions
Opening the package, you get a single, flexible rubber cover with two end caps connected by a thin strap. The material feels grippy but not sticky, which is a good thing for handling with gloves. Verified buyer reviews across 500+ units mention that the rubberized texture resists slipping on smooth scope bodies.
Installation is straightforward: you slide the larger end over the objective lens (the front) and the smaller over the eyepiece. The tension is snug without being a struggle, and it stays put even when you shake the rifle. The flip-up tab is easy to reach, and the spring mechanism snaps the cover open with a satisfying click.
Some users note that it takes a couple of tries to get the alignment perfect, but once it’s on, it feels secure.
| Material | Rubberized polymer |
| Fit – objective lens | Up to 50mm (common sizes: 30mm, 40mm, 50mm) |
| Fit – eyepiece | Standard 1-inch, 30mm, 34mm tubes |
| Flip mechanism | Spring-loaded hinge with thumb tab |
| Weight | ~1.5 oz (43 g) per pair |
| Color | Black |
| Water resistance | Splash-proof, not submersible |
| Warranty | Monstrum limited lifetime |
Daily-use experience
Performance
The flip-up action is the core feature, and it works well. The spring-loaded hinge flips the cover open with a positive snap, and it stays open out of the way. You don’t have to hold it, and it doesn’t block your view.
When closed, the rubber seals tightly around the lens edges, keeping out dust and light rain. Verified buyer feedback shows that after several hundred open-close cycles, the hinge retains its tension. Some users report that in very cold weather (below 20°F), the rubber stiffens slightly, but the flip action still works.
The cover doesn’t interfere with scope adjustments, the rings and turrets remain accessible.
Comfort & ergonomics
The rubberized texture makes it easy to grip, even with wet or gloved hands. The thumb tab is large enough to find quickly without looking. The cover sits flush against the scope body, so it doesn’t add much bulk.
That means it fits inside most rifle cases without snagging. The strap connecting the two ends is long enough to accommodate different scope lengths, but it’s thin and flexible, so it doesn’t feel like a distraction. I’ve seen comments from hunters who appreciate that it doesn’t rattle or make noise when walking through brush.
Build quality
The rubber feels durable, but it’s not armor. The material is a standard rubberized polymer that holds up well to UV exposure and moderate impacts. However, if you’re rough with it, like throwing the rifle in the back of a truck, the rubber can tear if it catches on a sharp edge.
The hinge is a simple plastic pin; it’s not metal, so it won’t rust, but it could break if you force it sideways. For the price, the build quality is appropriate. It’s not a “buy it for life” item, but it should last a few seasons of regular use.
✓ Pros
- Extremely affordable — costs less than a box of ammo — making it accessible for any shooter
- Easy to install and remove without tools, no scope disassembly required
- Rubberized grip stays put on the scope, even in wet conditions, and the flip-up tab is easy to use with gloves
- Stays closed securely during transport, and the spring hinge opens cleanly without snagging
- Fits common scope sizes (30mm, 40mm, 50mm objective) and standard tube diameters
✗ Cons
- Not fully waterproof — heavy rain or submersion can let moisture seep in, so it’s not ideal for swamp hunting
- The rubber can degrade if left in direct sunlight for long periods, leading to cracking after a year or two
- The hinge pin is plastic and may break if you twist the cover sideways, especially in cold weather
- Doesn’t fit extra-large objective lenses (above 56mm) or very short scopes where the strap is too long
Who should buy it
Buy it if you…
You’re a casual shooter, hunter, or range enthusiast who wants a simple, no-nonsense way to protect your scope lenses when they’re not in use. If you’re on a budget and don’t want to spend $30+ on a pair of covers, these are a great entry point. They’re also perfect if you own a rifle that lives in a safe or gun case and only comes out for range days or hunting trips.
The flip-up design means you can leave them on while carrying the rifle, then flip them open without fumbling.
Skip it if you…
You’re a hardcore tactical shooter or a professional guide who needs absolute waterproof sealing, or if you routinely expose your rifle to heavy rain, mud, and submersions. The rubber won’t seal out water completely. Also, if you have a high-end scope with a very large objective lens (56mm or bigger), these covers won’t fit.
For those cases, you’ll want a more robust solution like a hard-shell cover or a dedicated waterproof bag.
Better alternatives
If you want a more durable option, consider the Butler Creek Flip-Up Scope Covers, they use a center-hinge design and are made from a stiffer polymer that resists tearing. Another alternative is the Vortex Defender Flip Cap, which is a rubberized design with a clear lens option that lets you see through it while closed. Both are more expensive but offer better long-term durability.
Frequently Asked Questions (FAQ)
Will these fit my scope?
They fit most common rifle scopes with objective lens diameters of 30mm, 40mm, and 50mm. The eyepiece end fits standard 1-inch, 30mm, and 34mm tubes. Measure your scope’s objective lens outer diameter to be sure.
If you have a 56mm objective, these won’t stretch enough.
Are they waterproof?
No, they are splash-proof, not waterproof. They keep out light rain and dust, but if you drop your rifle in a creek or hunt in a downpour, water can sneak in through the gaps. For wet conditions, look for a sealed neoprene cover or a hard case.
How do they attach?
You simply stretch the rubber ends over the scope’s objective and eyepiece. There’s no adhesive, no screws, and no tools needed. The rubber grips the scope body, and the strap connects the two ends so they don’t get lost.
Do they affect scope zero?
No, they add negligible weight and don’t touch the erector system or turrets. The cover sits on the outside of the scope tube, so it won’t shift your point of impact.
How long do they last?
With moderate use (range trips every few weeks), most users report they last 1, 2 years before the rubber starts to crack or the hinge loosens. If you store them in a cool, dark place away from UV, you can extend that life. For the price, they’re essentially disposable.
Final verdict
4.3/5 stars, The Monstrum Rubberized Flip-Up Scope Lens Covers deliver exactly what they promise: simple, affordable protection for your rifle scope. They’re not the toughest or most weatherproof option, but they cost less than a typical lunch out, and they work as intended. If you’re looking for a no-fuss cover that won’t break the bank, these are a solid choice.
If you need heavy-duty waterproofing or a precision fit for oversized scopes, look elsewhere.
Affiliate disclosure: This post contains affiliate links. If you buy through one of these links, I may earn a small commission at no extra cost to you. It never changes my recommendation, I only suggest gear I’d actually buy myself.
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