Ref - L-OS71605300
The general use glow plug recommended by O.S for many of their engines. It is the standard OS Glow Plug, if you have a OS two stroke engine then starting with one of these will not see you go far wrong. Recently the A3 has been renamed the O.S 6 - if you ask for an O.S 6 or an A3 - we know what you mean!
Glow plugs are considered to be consumables - But by using a low voltage to start ( under 1.5 volts) and not burning the plug dry, you prolong the life of your glow plug. It is also worth washing out a new engine after running in to prevent small particles shorting the plug and destroying it. Blowing plugs on new engines is less common now a days, but is still something that can happen.