These pistons are produced for Triumph 650 c.c. motorcycles by Emgo and include the pair of pistons, two wrist pins, and four keepers as pictured. These pistons are a stock 9:1 compression ratio. Piston rings are sold separately. NOTE: Triumph 650 c.c. bikes have a 71 mm bore standard, 0.020" is 71.5 mm, 0.040" is 72 mm, 0.060" is 72.5 mm, and 0.080" is 73 mm.