i use these on my engines.
stainless steel and double o-ring's.
do not leak
NICE.
I have a Stainless Steel fetish tho.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
No leaks on mine since I replaced them all.
It's a bit fiddly getting the rubber seals square as there is plenty of spring!
They are made of ali with double o-rings.
I had a few of those OEM repair tubes, brand new, and every one leaked, badly.
On wbx's I use the Jaycee anodised Al ones intended for ratio rockers, so the outboard end is made larger. You flip them around so the larger end is inboard, and use the shims they supply that back up the seals. They fit good, have never leaked, and there's still room in the head end for 1.25 rockers.