... YOU FOAM): mainly used in insole for medium and top grade shoes, case also ok. advantage: eco-friendly, breathable, durable ... , antibactreial, sweat absorbing.2)PU FOAM(ORTHOLITE): mostly used in insole for medium and top grade shoes, case, sport equipment etc ... liquid, equipment filter etc. 30ppi PU Filter Foam/Reticulate Foam 30ppi PU Filter Foam/Reticulate Foam 30ppi PU Filter Foam/Reticulate Foam