Clear Primer, NSF listed (National Sanitation Foundation). Clear aggressive primer used on PVC (polyvinyl chloride) and CPVC (chlorinated polyvinyl chloride) pipe and fittings. Low VOC (volital organic compound) solvent cement. Removes surface dirt, grease, and grime as well as softens the pipe surface to allow a fast, secure solvent weld. NSF listed meets ASTM (American Society for Testing and Materials) F656.