HSP High Quality No 4 Glow Plug. Will suit all Nitro engines, and is a good all rounder. Has a nice bright glow, and heats up instantly. Coil is made from a Platinum / Iridium mix. The Platinum content ensure longer life as it is a harder material, and the Iridium is an excellent conductor of heat ensuring maximum efficiency.
Not suitable for professional racing.
Glowplug Equivalent Chart
HSP HPI OS
3 5 8
4 3 LC4