Also should be noted that the original Cox heads are 1.5 volt heads and NiCads spend most of their time at 1.35 so you don't get as good of a glow making starts harder. The best unit I've used is that silly, Black 2 D cell battery holder from COX. It'll give you a whole summer of starts on 2 cells. Get the old Cox, Yellow clip and fill the yellow handle full of silicon so it doesn't wobble. In fact, get several. You can also just scuff the batteries with some 400 grit paper and solder leads just to that, wrap with tape or heat shink and use that till the battery is dead.