The black magnetic micro sensor, NC (normally closed), limit switch OMS 08006003, is a reed sensor used for contactless position detection. It works together with a magnet: in the absence of a magnetic field the contact stays closed (NC), while the magnet approaching momentarily opens it, signalling the opening or closing of a door, a protective guard, or the end-of-travel of a moving component.

Being a reed contact sealed in a vacuum glass capsule, it has no mechanical wear and is suited to intensive-use applications. Replace it when the limit signal is intermittent or absent, when the machine no longer recognises the closing of a safety door/guard, or when it reports a limit-switch error even though the component is physically in the correct position.