duvide Kickstraps are for strapping on to feet (bare feet or with shoes) or ankles.
They offer a unique way to train resisted kicks, e.g. the Muay thai push-kick or Karate side kicks. Outer thighs and hips can be strengthened by lifting legs sideways.
This is a video of the Kickstraps with a discontinued version.
The current version has now a heavy duty elastic shock cord.