Mounts to 20mm Picatinny rails
Takes the BB hit so your optic doesn't have to
Don't take the risk!
If you're attached to your optic and don't want to see it shot out, a Lens Protector is what you need! The Delta Armory Lens Protector for 20mm Picatinny Rails is designed to mount in front of your optic and take the hit so your sight stays safe. The protector can be flipped down for storage and is constructed from Perspex with an alloy mount. 
If you're worried about getting your optic shot out, this is a far cheaper alternative to buying a new optic should the worst happen. If you'd rather replace a lens protector than your favourite optic if you get unlucky next skirmish, the Delta Armory Lens Protector for 20mm Picatinny Rails is essential!