A Medium Gapper™ leaves a medium-sized space in the 3rd valve ring. It's width is .26 inches.
The Gapper™ is designed to take up the gap between your finger and the 3rd valve slide ring. The size Gapper™ each player prefers depends on a variety of factors: brand of instrument, taper of finger, etc. However, most players find that, with Bach instruments, the size of Gapper™ corresponds with ring size in roughly the following way: XS - 5; S - 6; M - 7; ML - 8; L - 9; XL - 10. We also offer a size guarantee. Check our return and refund policy below.