Curtis Bags Trombone Thumb Rest One Size Black Please refer to the product description below to check HOW TO USE. / A signatory is required upon delivery of the item. Size(inches) : 2.16 x 2.75 x 0.35 Material : ABS(Acrylonitrile Butadiene Styrene) Details : Curtis thumb trest while supporting the weight of the instrument, hand and wrist, reduces tension and stress on the arm and not to put excessive pressure on the body while playing trombone The size may differ by 0.2-0.4 inches depending on measurement methods. / The color displayed may vary depending on your screen.