PEX not all inserts are created equal it seems

[mike]

I'm a 1st time user of pex tubing for heating and got some inserts from 2 different suppliers (oooh don't ask why). They sent these.

Is there a reason for the O rings on one - or are they just better quality?

[Tim Watts]

The right one looks like genuine JG Speedfit. Potentially offers a second line of defence over the one O ring in the fitting so I guess it is "better" but not essential as a copper pipe into the same fitting will only reply on a single O-Ring.

[Dave Liquorice]

Second line of defence and the one without the O rings should be the one used with compression fittings.

--28mm-SIZE-PIPE---ACCESSORIES/Inserts.aspx

[Tim Watts]

That figures - thinking back it is basically the same part as the MDPE insert I used making an MDPE to copper compression joint.

[Grimly Curmudgeon]

Purely for a push-fit design from the same maker, IWT. O-rings would be a liability on a compression fitting.