The water heater has threaded nipples on the top that for some reason have rubber washer on top. They do not specify what to buy to screw on them to make a seal. I had to buy some 1/2 inch female to pex and pretty much completely reconstruct the piping to make the connection. On most water heaters of this type you can put a braided line, 1/2 to 1/2 and connect a sharkbite 1/2 or 3/4 on the copper, or pex pipe to 1/2 in male threaded to the water heater, and be through in minutes. Get in touch with me if you need more explanation.