THESE ARE GREAT QUALITY AFTERMARKET PISTON KITS.. THEY INCLUDE PISTON RING SET PISTON PIN PISTON PIN CLIPS @ 90CC STANDARD_PISTON_KIT 50.00mm ALL ATC90 CT90 ST90 CL90 S90 SL90 CM91 1/22S (TFK90PIS) (S1417) TFK90PIS (S1417) @ *HEAD_GASKET CT90K0_to_K4 (ATC90_F/N_TO_1113934) ALL_S/SL/CL90'S ALL_CM91 12251-028-030 1/20M (R2192)THIS IS THE ALL ROUND HEAD GASKET THAT THE CT90K0 THRU K4 TOOK AND THE EARLY ATC90'S THE NEWER CT'S AND ATC'S HAVE THREE NOTCHES IN THE HEAD GASKETS. THE ALL ROUND HEAD GASKET WORKS FOR (CT90K0 THRU K4) OR AN ATC90 WITH A ENGINE SERIAL NUMBER SMALLER THAN 1113934 R2192