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 newer King's 600 series and 2055 Silver Flair Trumpets and many other King & Conn Brass Instruments, like the King 1121 & K20SP marching mellophone.  Not for older Silver Flair trumpets with the larger top action spring (not internal to the piston), for that kit see my Item ID: 274333961700.  For a King marching trumpet kit, see my item ID# 274245610201.  Contact me with your model if you would like to verify.