That is very cool.Interesting. I have not seen self stick ones before. I checked on line and these are 1/4" diameter. Regular sax bumper felts are 3/8 or 5/16. I don't know if these will fit too loose or not. I am assuming you are putting them in the adjusting screws that go in the key guard. I typically just remove the screws rather than take the entire key guard off. It is usually possible to use the old felts as a guide to know how long they should be, unless of course they are missing. I like to make the felts the exact length that allows the adjusting screw to be flush with the top of the guard. To me it looks better that way. To cut the felts to length I chuck the screw with the felt installed into my bench motor and use a single edge razor blade while it is spinning to make a clean, perpendicular cut. If you don't have a bench motor, a cordless drill in a vice makes a good "poor man's" substitute.