This pattern of steel arm was introduced by the GWR in 1930, replacing the wooden design (S0014) which had been in use since 1887. These signal arms were used for all new installations after 1930, and although usually associated with tubular steel posts (T200A, T250, T18), also gradually replaced the wooden arms on their original wooden posts. The design was adopted by BR, Railtrack and Network Rail, and a very few lower quadrant semaphore signals are still being installed today, where replacement by colour lights is inappropriate. A few signals combined the new pattern arm with the old pattern spectacle plate. An S008/7 bracket platform is included in the pack.
The actual size of the fret is 85 x 54mm; it is etched in 0.012″ brass.