Product Information:S-9891 Pressure Cooker Gasket inner diameter 10.5 inches, outer diameter 11.5 inches, thickness 0.2 inches (hand-measured; slight variations may occur) Product Features: This mirro pressure cooker gasket effectively seals to maintain pressure, prevents leaks, and improves cooking efficiency. Replacing an aged gasket restores the pressure cooker to normal operation. Compatibility: S-9891 Replacement Gasket for Mirro/Mirro Matic Pressure Cookers for Models M-0396 & M-0398. (including those with the -11 or -35 suffix) High-Quality Material: This gasket is made of premium rubber, offering long-lasting elasticity and resistance to high temperatures and pressures. It resists aging and deformation, ensuring a stable seal and a longer service life. Easy Installation: First, remove the old gasket from the lid groove. Then, carefully insert the new S-9891 gasket into the lid's sealing groove, ensuring it lies flat without wrinkles or lifting. The replacement is quick and straightforward. When to Replace: Replace the gasket promptly when it becomes hardened, cracked, leaks air, fails to maintain pressure, or does not seal properly, or after 6–12 months of use, to ensure the pressure cooker operates safely and efficiently.