"All it needs to do is sit under the sink and not leak. No such luck. A very slow leak from the o-ring (like the previous reviewer). These must have some design or manufacturing issue. I used the 32mm anti-vac trap elsewhere from the same mfg and it was fine. Need to take this thing back now and get a refund. Not using another one that's for sure."
"Some months ago, I bought a 32mm version of this. It leaked and I had to replace it with a different brand. Thinking it was just a one-off, I bought two 40mm ones for another job a few months later. Both of the new ones leaked as well.
All of the traps leaked from the same place - the o-ring joint between the two halves of the bottle. There is no visible damage to any of the parts but no amount of fiddling with the o-ring seating or the tightness of the joint makes any difference - they still leak.
They'd be good value if they worked but that's no good if they just dribble dirty water all over your stockpile of bin-bags."