I have used the 177 type and I do not like them. The gasket is kind loose on the pipe so it won't stay in place on its own. When youre changing them on a vertical run it feels like you need 3 hands to install them. And the gaskets for the 77 are different and not interchangeable to the 177 so now you'd have to stock 2 different gaskets per pipe size. Im sure they're fine and work wonderful and I'm just set in my ways but I'm just not a fan
