Mahle Original Standard Piston Ring Sets 4.00" Bore Cast # 50564.STDMahle Original Standard Piston Ring Sets 4. 00" Bore Cast # 50564. STD Mahle Product Details Piston Rings, Standard Piston Ring Sets, Cast Iron, 4. 000 in. Bore, 5 64 in., 5 64 in., 3 16 in. Thickness, V8, Set Bore (in.): 4. 000 in. Bore (mm): 101. 600mm 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