I am currently making an exoskeletal AK prosthesis for an elderly woman. She has a crude leg that was made in russia that has a very large valve in it with approx. 2 1/4″ opening. She like it because it is easy to get her fingers inside to grab the sock when she pulls herself in. Does anyone know if and where i can get a vale of this approximate size? If not I think she will sentence me to the Gullag in Siberia.