Springs are based on weight. Rule of thumb is go to the spring above your weight, otherwise you will be bottoming out soon (Where you compress the spring all the way down so you touch the floor). So if you weigh 55kg, get the springs for 60-70kg, 62kg get springs for 70-80kg, and so on.
Powerskip differences:Powerskips are made with Aerospace Aluminium. ProJump are made with normal Alu Alloy. This make Skips a LOT lighter.
Powerskips have fibreglass springs with the best energy return on the market. ProJump use a fibreglass/carbon fibre compound. This means that you have to push harder on ProJumps to get the same height.
Powerskip have a white/brown replaceable sole, much like a shoe sole. ProJump use a replacable black rubber sole or "hoof" that simply bolts on. The Powerskip sole offers a little more grip and is less likely to mark surfaces.
Powerskip are the original Jumping Stilts that all other designs are based on. ProJump pay the inventor of PowerSkips a royalty fee to be allowed to sell their brand.
PowerSkip are generally just higher quality, precision made and provide better bounce.
Having said all that, ProJump are still great value for money and perfect for learning on, and will last you a long time.
ProJump elites are the next generation stilts, the ones displayed on the ProJump site are discontinued and will not be sold due to mechanical/safety problems with them. They were due to go on Sale about a year and a half ago but they were pulled as FlyingLocust (The company that makes ProJump, PoweriZer, PowerStrider, FlyJumper, AirTrekkers, AirRunners, SpeedJumpers, and JollyJumpers) started selling them whilst they still had some flaws. They were known as "PowerZer UpWing" and "SpeedJumper Redoxx" elsewhere, and AirRunner still sell them in Australia, I am assuming for a backlog of stock.
The NEW ProJump Elite (I'm am unsure if they are still going by that name - hopefully naz will clear it up) are based on a new design, taking things from the Upwing design and adding/taking bits away, providing a much better quality stilt. There are some pictures on here if you take a look around
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