Instead of an adjustment nut for tightening, the Self-Adjusting Pipe Wrench has a spring-loaded, heel-and-hook jaw that automatically adjusts to fit pipe and other round surfaces up to 3 inches in diameter (depending on model). The jaw aggressively 'bites' the workpiece to both ensure a secure grip and facilitate ratcheting action. Quick adjustment mechanisms allow one to apply and remove the wrench using just one hand. Made of aluminum, cast iron, or forged steel, the tool is available in 10-, 14-, and 18-inch sizes.