*This is printed in TPU*

My family likes to hang their water bottles from their backpack straps and things like that. When you go through doorways and things the bottom of the bottle likes to bash into things. This is just to dampen that clang and prevent any damage. It also makes it more non-skid. I just added a removable TPU bumper to the bottom. The interior diameter of the bumper is 74mm so these will fit cups and bottles with a 74mm bottom or about 2-7/8". TPU is a little stretchy so you can probably get away with a slightly larger one as well. You can scale them up or down to suit whatever you want based on that dimension. Let me know which other cups it works on and whether you had to scale it and I will add them to a list.