The FESTO SMT-8G-NS-24V-E-2,5Q-OE is a magnetoresistive proximity switch in the SMT-8G series, built for pneumatic cylinder position sensing. It operates at 24 V and comes with a 2.5 m cable, so it drops into a standard 24 VDC control circuit without a separate power supply.
The magnetoresistive principle means it detects the piston magnet through the cylinder wall — no physical contact, no wear on the sensing face. That matters when you're cycling a cylinder hundreds of times a shift; a reed switch would fatigue, but this gives a clean digital signal as long as the magnet passes within range. The 2.5 m cable reaches from the cylinder mount back to a terminal block or M8 connector in the valve manifold.
The SME-1 is an older magneto-inductive switch with a 220 V AC operating voltage and a clamping-angle mount — completely different supply and mounting scheme. The SMT-8G-NS-24V-E-2,5Q-OE runs on 24 VDC and uses a T-slot or dovetail mount common on modern FESTO cylinders. They are not drop-in interchangeable; swapping requires checking the cylinder groove profile and the control voltage.