This is the extension mechanism only, not the switch body; you pair it with the corresponding A3 switch and enclosure door kit.
On a panel door, the extension handle mates with the A3 switch's rotary actuator through a door interlock mechanism. The padlock feature accepts up to three padlocks (shackle diameter per the switch's specification) to satisfy OSHA/NEC lockout requirements. Verify the door cutout dimensions and handle projection against your enclosure depth before ordering — the extension adds length beyond the switch body, and a shallow cabinet may not clear the handle travel arc.