Pos-T-Vac Mach Ring Large #7 - REPLACES URMACH1TENSIONRING7.Mach Ring 7 (L) inside diameter 10.5mm (.430 inches).PosTVac Mach Ring has a thick center, creating an evenly dispersed tension and comfort over a wide area.The Mach Ring will maintain adequate firmness for approximately 30-40 uses. Latex Free.