24 VAC Low Water Cut-Off for water boilers, probe type, 3/4" NPT, heavy-duty electro-mechanical design for long life, automatically shuts off burner in low water condition to prevent boiler damage, auto reset feature automatically re-energizes circuit upon return to safe water level, includes short EL1214 SV probe for easy installation into standard malleable iron tee, low maintenance no moving parts to wear or stick, rugged construction designed for the heating professional.