This starter pack contains a fret of 32 AC3/3 delayed action autocouplings for use on 3mm and 4mm finescale layouts. This style of coupling is particularly popular with EM gauge modellers.
Also included are 2m of BW brass wire, 2m of NSW4 nickel silver wire, 1m of SIW4 soft iron wire, and four 4MAG permanent magnets. A cheaper trial pack (T/AC3/3) is also available, with eight couplings and MP4 mounting plates, wires and one permanent magnet.
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.
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. The magnets are 25mm long, 7½mm wide and 4mm deep.