UniSeals

[mr_alberta]

Here's the blurb on Aquatic Eco Systems about them:

Originally Posted by Aquatic Eco Systems

Reduce costs! Why use an expensive bulkhead when you can use a Uniseal®? Just drill a hole in the pipe, tank or bucket, insert a Uniseal®, then put some Windex® on the end of the pipe and push it in. It’s that easy! Feel like rubber, but they are made of DuPont Alcryn® rated to 40 psi and warranted for 25 years. They are immune to cold, will not harden and hold pressure and vacuum. The sizes below correspond to standard Schedule 40 PVC pipe. Fit tank wall thicknesses up to 1/2". Made in USA.