jumping jacks

[puzzle]

I have a pair of jumping jacks that are like roller skates, but they have springs instead of wheels.

:?: What's the jumping jacks? please.

 

[Rover_KE]

I've never heard of them, but the description given sounds clear enough.

Rover

 

[JMurray]

What's the jumping jacks? please.

puzzle.
It sounds to me like the skates-with-springs that you have are called jumping jacks as a brand name. The original jumping jack was a kind of puppet whose legs and arms jumped up and down when you pulled the strings.
http://en.wikipedia.org/wiki/Jumping_jack_(toy)
These days "jumping jacks" usually refers to a type of exercise where you jump in the air with your arms and legs spread out in a star shape.

not a teacher

 

[Tdol]

There's a firework called a jumping jack- could the springs look like one: http://www.thegreenman.me.uk/images/touch3.jpg

 

[puzzle]

Thank you all.;-)