Genuine LiftMaster 50-12949 rolling door interlock switch, also known as 50401 for the Maxum industrial DC operators.
Fitment: LiftMaster Maxum JDC, RJDC, JHDC and TDC industrial DC operators.
Also sold as 50401. Sectional doors take the 50-13529.
Ordering the right part depends on the full model number, which is printed on the operator label. Call GateHouse Supplies if you are not sure — we service these units every day.