A seal is created when the pipe or insert is pushed past the O-ring eliminating the need for excessive tightening. On fittings up to 32mm, simply hand tighten the Plasson nut for a completely leak-free system. On fittings 40mm and above, hand tighten plus 1/2 turn with wrenches. Plasson fittings have proved to be the most reliable connection systems for poly pipelines in Australian conditions for over 40 years. Suits Blue Stripe Metric Polyethylene (PE) Pipe