Check Valves
  Lightweight aluminum O-Check ® features a dilating O-ring as the
only moving part. Quick to open, quick to close, O-Check ‘out-flows’
the competition, will last millions of cycles (factory tests to
50 million cycles show no discernible wear) and always provides
positive sealing (no bubble leakage). Standard NPTF sizes
1 / 8”, 1/ 4”, 3/ 8”, 1/ 2” and 3/ 4”.