30mm eye piece - Butler Creek Eyepiece Flip-Open Scope Covers

I purchased this 30mm cover for my Trijicon Credo 1-6× variable optic. It fits snug on the objective end (muzzel side). I also have a 43.2mm size for the ocular end. They stayed on during an operation in rugged terrain and dense brush on a hot day. I have not used them in cold or wet weather, so not sure if they'd slip off in those conditions like Vortex ones do. My main purpose for them is to protect the lense during storage. I did have to rapidly deploy my rifle recently and had no problem opening the covers. Overall, definitely good buy for the money but I cant speak on durability yet.