
PG21 Cable Gland Size Guide: 28.3 mm Thread, 13-18 mm Cable
PG21 clamps 13 to 18 mm cable through a 28.3 to 28.5 mm hole, and its real competitor sits 0.3 mm away at M28. Why “PG21 vs M20” is the wrong question, and why the hole rather than the cable decides this size.







