Heavy gauge plastic sheet. Transparent, long lasting, crystal clear window material. 4 mil. thickness. No. NFG 3625: 75 lineal ft., 36" wide No. NFG 4825: 75 lineal ft., 48" wide No. NFG 36P: 25 lineal ft., 36" wide No. NFG 48P: 25 lineal ft., 48" wide