Made for sampling potable water supplies, lakes, swimming water, streams and effluents from any environmental source and industrial wastes. Has a non-nutritive, non toxic tablet of sodium thiosulfate as a neutralizing agent. Meets with official water sampling container requirements. Purple closure tapes distinguish sodium thiosulfate bags from other Whirl-Pak bags. The 120 ml size has a 100 ml fill line mark. Packed sterile.