Spira Shoes Are The Spira Shoes Effective And Also Are They Legal? General Description Please?

Are the Spira shoes effective and also are they legal? general description please? - spira shoes

With a view to buy Spira shoes / racing flats with technological wave spring. They say that it significantly reduces muscle fatigue and can be used to increase the speed. I wonder if this is true. If you have these shoes, you could tell me if they are. and if anyone knows any information about them please give me bescheid. Everything is useful
Thank you:)