36" AFO Plastic Liner Bags500 bags box A 36x5. 5 protective, polyethylene bag used by clinicians as a liner to separate the layers of hardening resin and casting socks from the patients skin. This liner is best used when trying to cast for a majority of the lower extremities (foot, ankle, leg, knee and thigh). Each purchase of the 36 AFO Plastic Liner Bags includes one box full of 500 individual plastic bags.