I had never used these or ever heard of anyone ever using these until I saw someone using them to connect rainwater collection barrels together in 2020. For the price, I figured it was worth trying. It was a good decision. Bulkhead fittings can drive a person crazy trying to get them threaded on a curved surface, and for a closed-top 50 gallon plastic drum, a bulkhead fitting is extremely difficult to get installed. Uniseal adapters are ideal in this application. Cut the hole, push the Uniseal into the opening, then push the PVC pipe into the opening. It's literally that simple. I will be buying these again.