This fret contains 40 Mk1 original design autocouplings for use on 3mm and 4mm finescale layouts. Delayed operation is not possible with this coupling unless modified. For delayed operation, purchase AC3/3 instead.
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).
The actual size of the fret is 69½ x 108½mm; it is etched in 0.012″ brass. Each coupling is 24½mm long and 7½mm wide.