those days sound fine, and we suspect most brands r the same factory makin em, but sellin em 2 ppl who put diffrent patents on em
oooooooooohhhhhhhhhhhhh that's a very slippery rd you are on....
First of all there is only one patent holder - Alexander Bock. For any stilt sold a fee must be paid to him and any importer must have his permission before they sell them... As far as I'm aware selling them unbraded is illegal as you are breeching copyright and patent laws.
Pro-Jump have this on their website:
This product is Patent protected throughout the UK, USA and most of Europe.... Pro-Jump are fully authorised by the original inventor and can be sold under the trademark Pro-Jump.
At present in the UK only a few companies are allowed to sell these stilts legally the companies are Pro-Jump, PoweriSer, PoweriZer, Fly Jumper and 7 league boots.
No other seller is legally allowed to sell them. It's not up to the manufacturer to pay the patent royalty fees its up to the importer/seller to make sure what they are selling is legal.
If I was you I'd tell you grandad to check with the Bocks if the stilts they are selling are legal or risk getting a hefty fine! Also unless you are sure they are legal and I wouldn't mention it on a public forum!!