ActronAir MPW40 Auxiliary Contact MPW40-ACBS-20 2xNO is a side-mount auxiliary contact block for WEG MPW40 contactors, providing additional normally-open or normally-closed contacts for signalling, interlocking, and control circuit logic in ActronAir commercial outdoor unit control boxes. Auxiliary contact blocks must be matched to the parent contactor model -- confirm compatibility before ordering. Isolate power at mains before replacing any contactor auxiliary contacts.