Found a couple of these (Teng 3892AG-E1) on the bay, assuming they're the same as you use? On a tool website they show two options, certified and not, if it's the same tool and i'm just using it at home does it matter which?

This one looks great but doesn't say certified: http://cgi.ebay.co.uk/TENG-TOOLS-389...3A1%7C294%3A50

Opinions?