That switch used to have a insulating (cardboard) cover in it, the retaining screw is still there, (it's a ITE disco) ,another thing is the switch is a 1Ø 2 W , no provision for a neutral, & if A/C data plate states "maximum fuse or HACR circuit breaker size __" a non fusible disco may not be used.

BTW, other then the insulating cover, the switch is complete.