O.S. Glow Plug Specification

Type	Description
No. 0	Economically-priced medium-heat plug
No. 1	Hot-rated plug
No. 3	Medium-heat plug
No. 5	Cold rated plug
No. 7	For 2-stroke R/C engines where a shielded element "idlebar" type plug is specified
No. 8	Most widely used O.S. glowplug. Recommended for most current O.S. (and many other) 2-stroke engines
No. 9	For 2-stroke engines
Type F	Special long-reach plug recommended exclusively for O.S (and many other) 4-stroke engines
Type RE	Special long-reach plug designed exclusively for O.S. Wankel rotary engine
A5	Recommended for most current O.S. (and many other) 2-stroke engines particularly for 1/10th & 1/8th scale off-road car engines
A3	Dependable O.S. quality makes A3 the most durable and longest-lasting glow plug available at an economical price
R5	Recommended for high-nitro fuel and high r.p.m. engines, particularly 1/8th track racing car engines