Very well-built, no leaks over the last month in use with a relatively high pressure system.A word of caution that I suspect most people will consider just common sense: if drilling into the metal flanges on the top or bottom of the unit to enable use of bolts for mounting, you MUST use a backing material like scrap wood, or a depth gauge on the bit/press to prevent damage to the copper tubing. Even on a drill press, it's very difficult to stop the forward travel of the bit after getting through the metal flange, and there's only a centimeter or so to spare before you find yourself destroying your beautiful new heat exchanger. Having made this mistake, I can also advise that repair putty is the perfect fix. I used Loctite 1999131 All Purpose Repair Putty, and had a watertight seal in 10 minutes without any leaking.Perhaps the manufacturer would consider pre-drilling the flanges for mounting, to eliminate the need to perform this risky modification.