This fret contains 32 Mk3 delayed action autocouplings for use on 3mm and 4mm finescale layouts. This style of coupling is particularly popular with EM gauge modellers.
The recommended minimum radius curve for these couplings in 4mm scale is 4′, hence the finescale description. For tighter curves, use the MP4 mounting plates, which allow operation down to 2′ radius. They also have the added advantage of making the couplings easier to fit.
To fit and make the couplings fully operational, you will also require BW brass wire, NSW4 nickel silver wire, SIW4 soft iron wire, and permanent (4MAG) or electromagnets (PK MAG). Alternatively, you could just purchase the S/AC3/3 starter pack, which contains the fret, the wires and four permanent magnets. A cheaper trial pack (T/AC3/3) is also available, with eight couplings and mounting plates, wires and one permanent magnet.
The actual size of the fret is 68½ x 107½mm; it is etched in 0.015″ brass. Each coupling is 24mm long and 8mm wide.