"I have used a few of these couplers without any problems, they are easy to securely fit without leaking due to the hexagon nut on the inside allowing a good tight grip. It would benefit from two washers as other reviewers have said, but that would not put me off buying this item again."
"Unlike some of the rubbish tank connectors you can buy, this has a hexagonal nut on the inside so you can actually tighten the fitting up properly.
Good quality fitting, they do come with a rubber washer for inside the tank. The only thing I would like to see is a large plastic washer for the outside but that is nitpicking. For the price you really can't go wrong."
"This is a nice solid tank coupler, and I liked the fact that the flange inside the tank is hexagonal so that you can grip it while tightening it up. It's also very affordable. My only gripe is that they don't supply a fibre or rubber washer to seal the inside, so you have to hunt around to find one that fits! Other than that, a great product."