The gas can vents are well made and the installation goes quickly. They work well but the caps need a lanyard so that they don't get dropped or lost. The package comes complete and they are easy to install. Overall very well thought out.
Pros
I installed these in all of my gas cans. They were great with no leaks, makes pouring a lot easier.!
Cons
They allow air in so empty is at least 3 times faster, ya-hoo