Both knees affected but still only one compartment in each knee. **If using on one side only then look to comfort insoles to balance the resultant height of the opposite shoe insole.
The material on the wedged insoles is a poly urethane, molded into the intended wedge. It is a closed cell urethane so it will not absorb fluids; i.e. sweat. It is easily compressible with each step with excellent material memory to immediately return to the original shape. It will retain its shape and effectiveness up to one year with constant wear under customary use.