Ok a semi sensible answer
Normally PoweriSers with an "S" will have Poweriser stamped on them in a few places
PoweriZers have PoweriZer on the calf pad and on the rubber stop under the foot (I think)
Pro-jump have Projump in the same places as above
All of the above are Legal in the UK
Any thing else your on your own and if they cost more than £100 I would walk away and buy a set of PJ's for £135
Just one thing to add I have met a few people who have bought the new PoweriSers (the ones with cuffs ) and are very unhappy with them one guy actually said they fell apart round him over a very short time
But if they are the older ones with knee bars not cuffs they seem good
Finally I wouldn't buy a used set of any type unless I knew the seller well enough to know how much use and how hard they had been used
(a week with tundraH is like a year with any other bocker
)
Or if I was buying them for spare parts and they were very cheap (Sub £40)
Jason