This pressure canner has an exclusive threaded escape valve, impossible to misplace. It has adjustable pressure for 5, 10 or 15 lbs. and lowers cooking time. A fully detailed instruction manual provided. It does not open while there is pressure inside. This canner is UL approved and will hold 30 1/2 pint, 16 reg pint, 14 wide mouth, and 5 quart jars.