I was going to use these plugs to seal the fresh water storage barrel in our RV, but when I tried to install the plug in the barrel the threads were so tight that the recommended torque was only about 1/3 the plug of the Length. After removing it, I saw that the part was "wavy" due to deformation of the overmolding around the 4 clamping lugs. Really disappointed with this product, no point in sending it back from New Zealand for a refund as the postage is more than the value of the product. Even if they could be screwed all the way in I doubt they would seal properly as the gasket would only compress at the four 'high' points and not the 'low' points. The two Buttress threaded plugs I bought from the same company seemed to work great, but these NPS threaded plugs were a waste of time and money.