King & Conn OEM Trumpet & Mellophone valve tune-up kit, easy to install. Bumper washers (O-rings) are for 1st and 3rd slides (Silver Flair). Fits King's 600 series and 2055 Silver Flair Trumpets and many other King & Conn Brass Instruments, like the King 1121 & K20SP marching mellophone. Contact me with your model if unsure. Not for older Silver Flair trumpets with the larger top action spring (not internal to the piston), for that kit see my Item ID: 16417.