Chromalox 241-054261-005 is the A-20 ring heater—a chrome steel-sheathed, single-heat heating element rated for 120 V and 300 W. It uses two terminals for a single-wattage on-off switch or thermostat and is designed for single-phase operation as part of Chromalox's A-Series (PCN 135351). The heater measures 3.97 inches in outer diameter (3-31/32 in), with a 1.69 inch inner bore and a thickness of 0.31 inches, delivering about 12 watts per square inch of heat-emitting area. This configuration is cataloged within Chromalox's A-Series ring heaters (PCN 135351), confirming chrome steel sheath construction and 120 V, 300 W, single-heat operation.
