The A3PP42-600R-91 is a 2-position main push-pull actuator in a 44mm red operator with a 1NO+1NC contact block. This is the type of mushroom-head push-pull used for emergency stop or main disconnect stations on machine panels — the pull-to-reset action stays latched until deliberately released.
The 44mm operator diameter is a standard panel cutout size for heavy-duty pushbuttons, typically mounted through a 30mm or 22mm hole with an adapter. The 1NO+1NC contact block gives one normally-open and one normally-closed set for dual-channel safety circuits or separate indication and control paths.