They should be available at any Home Depot as well, in the drip irrigaton section.
I used one of these and it works great, just becareful with the water pressure, because you can generate a lot more PSI than your boat will ever see in the water. You don't want to blow out the O-rings in your cooling can.
The nice thing is that if it doesn't leak with the house water pressure, you can be sure it won't leak when you are running it at the lake.
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