Good quality rubber and hole diameter is perfect, I put it on a normal left stick without problems, on the right stick there was original rubber, partly gnawed by my dachshund. I tried putting it on top of a piece of gum in case it needed extra thickness but it didn't go in properly so I ripped off the remaining gum leaving just a hard plastic thumb shaft and stuck the big one in. moved or pulled away and I play with claws and WZ a lot so this is a solid product. All in all great for not only adding size to your cane but also covering a worn cane.