Harold,
If you follow the link I think it might answer some questions for you.
They also have some pix of the devices.
http://www.goodfeet.com/Products/Alznner_Barefoot/alznner_barefoot.html
E. Reed Coleman, C.P., L.P.O.
Advantage P&O
3821 Southern Ave.
Shreveport, LA 71106
318.219.8800