It’s perfect for a keychain! I love it
I purchased this micro roller for my feet. I have had surgery on one and need surgery on the other. It’s important to do SMR work to get me by until I have surgery. I prefer this over a ball because it stays put and allows me to apply the amount of pressure that is appropriate for me.
Harder than I thought it would be, but that is not a problem. Just fair warning: very firm. I've used it for my feet and also to run down the side of my leg with my hand. Works well.