Cast Iron Piston Rings

Groove Depth	Grooves must be at least 0.015 inches deeper than the maximum radial wall thickness of the piston ring with a tolerance of +0.003/-0 inches. This is to avoid any possibility of the ring bottoming in the groove when the ring is compressed to its working diameter.
Groove Width	To permit the ring to slide freely into the groove, the groove must be at least 0.001 inches wider than the maximum piston ring width with a tolerance of +0.003/-0 inches.
Materials	Cast Iron.
Radial Clearance	The radial clearance between the cylinder bore and piston should be less than 1/3 of the radial wall thickness of the piston ring to ensure sealing effectiveness.

Model Number	O.D.	Width (in)	Wall Thickness
SPR-4002	4 in	0.187	0.135
SPR-6004	6 in	0.311	0.199
SPR-7002	7 in	0.249	0.236