It is made of bamboo charcoal grains and polyester or other fabric. With porosity of bamboo charcoal, the inner pore area of bamboo charcoal is 800 ~ 1000m2 per one gram. Bamboo charcoal performs in the role of absorbing damp and bad smell. Function: It can keep shoes dry, avoid skin illness-athlete's foot. It can be reused. Size: 80g, 160g.