Mahle Original Standard Piston Ring Sets 0.40 # 50564CP.040Mahle Original Standard Piston Ring Sets 50564CP. 040 Piston Rings, Original Standard Piston Ring Sets, Cast Iron, 4. 040 in. Bore, 5 64 in., 5 64 in., 3 16 in. Thickness, V8, Set Bore (in.): 4. 040 in. Bore (mm): 102. 616mm File Fit: No Gapless: No Gas Ported: No Top Ring Included: Yes Top Ring Thickness: 5 64 in. Top Ring Material: Cast iron Top Ring Facing Material: Cast iron Second Ring Included: Yes Second Ring Thickness: 5 64 in. Second Ring