Better control over the third valve slide, instantly. The third slide ring on a trumpet is designed to be one size fits all, or more accurately, to fit the largest possible hand size. Gapper comfortably takes up the gap between your finger size and the size of the ring on your trumpet. This gives students and professionals alike more immediate control over the third valve slide. Gapper will help even beginners with intonation, control, and comfort. Advanced players and professionals will wonder how they ever played without it. Available in multiple sizes and designed to fit a variety of trumpets and trumpet models.