The cross leg stopper attempts to correct bad posture by making it impossible for users to cross their legs.

While crossing legs is a very comfortable position, doing it for long periods of time can slow down circulation and is said to cause chronic back aches and slouching shoulders. Designed after a shark fin, Sharky the cross leg stopper was created to make it literally painful for men and women to sit in this pose.

The contraption can be inserted with the flat side up or down between the legs, which effectively stops the legs from subconsciously moving over the other. When inserted flat side up, designer Lucy Jung’s Sharky can also be used as a desk for taking notes as well.