T18 / T25 240V 500W GY9.5 Lamp. Tungsram quartz halogen replacement bulb suitable for fresnels and profile lanterns rated up to 500W with a GY9.5 lamp base/cap.
Essentially both T18 and T25 are the same lamp type but with a couple of differences. The T25 has a colour temperature of 3000K as opposed to 3500K on the T18. Physically both lamps are the same measurement, but there are differences in the filament layout.
Typically used in Strand Prelude F, PC, 16/30 etc and Quartet F, PC, 22/40, Selecon Acclaim F & PC amongst others.