Set of eight EAC-6108S Dome Top Piston Set for 1949-1953 MERCURY 3 3/16" bore for motors with 4" Stroke crankshaft. Proudly made in the USASelect from the following sizes: STD or 0.20, 0.30, 0.40, 0.60, 0.80, or 0.100 Oversized. Size options are chosen before adding to your cart.