Hey JayD
I hate those things and gave mine away, I use the other plastic thing.
I buggered a spark plug thread up with one of them long while ago and cost me to have it fixed!
I screwed it into the plug hole of a 44 and give it a twitch, thought she'll be right. Tried to crack the clutch off but was seized like a bugger (palm corrosion I suppose). When I finally cracked it the tool you show kinked in the thread of the plug and buggered the threads. I wound it out it was like recutting the thread. Made the thread egg shaped.
Looked bad, carefully screwed a plug in but when I tightened it ... it just spun, you know, that it's tighter but just a bit more then it goes loose again and so on.
So now, I only use the plastic thingo.
Look at the angle of the thread compared to the angle of the piston hitting it. It's like 45 degrees with leverage, not good, sorry, once bitten twice shy.
