If it is made (rebranded) by rothenberg it is shyte and robogrips must have been at the top of the shyte list!
If you want a decent set of adjustable cutters look for these
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They used to have (well mine have) an alloy handle but i see they are now plastic. I suppose that is what is called progress!
The knipex (K nipex!!! why don't they get someone who can say the word to advertise it) grips in the link above are good (for polished fittings) but no better gripping (infact probably less so) than a set of alligators or cobras. Mine only get used on chrome nuts and the like.
If you want something that will never ever slip because it is an impossibility, use stilsons.