I use 43 & 21 sized grips, and both small and medium size cots fit snug enough that it won't fall off, and isn't too tight. For me tape is good for a game or two, then needs to be replaced... I can use a cot for an entire practice session.

I initially tested these out by buying a small box of assorted sizes they sell at Walgreens, and they weren't that good... too thin... but at least I was able to check the sizes and get a feel for them. I found a thicker type on Amazon, and bought an entire bag of 750 for $20... and they've worked great. I use these black ones, because they look good, fit great, and aren't too thin... at 3 cents each. If you search finger cot on Amazon, you can find different colors, different thickness, and different materials.