I had a spare after loosing one and Swarovski sending me 2 as a replacement. When they arrived, I just happened to have the z6i off the rifle.
My Binos were the 10x42 EL's, my z6i is a 5-30x50. The ocular diameter looked very similar so I tried it
So being rubber and more robust (which wouldn't be hard) than Butler Creek, I can see these lasting years!!