This starter pack contains a fret of 32 AC4/3 delayed action autocouplings for use on 4mm scale layouts. They have also been successfully used in 0-16.5.
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/AC4/3) 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 2′. For tighter curves, use the MP4 mounting plates. They also have the added advantage of making the couplings easier to fit.
The actual size of the fret is 92½ x 144mm; it is etched in 0.015″ brass. Each coupling is 32mm long and 10½mm wide. The magnets are 25mm long, 7½mm wide and 4mm deep.