Reduce costs! Why use expensive bulkhead when you can use Uniseal®? Just drill hole in pipe, tank or bucket, insert Uniseal®, then put some water on the end of pipe and push it in. It's that easy! Feel like rubber, but they are made of MPR 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. Instructions for installing Uniseals -Drill hole to proper size for Uniseal with hole saw (see chart below for sizing). -Make sure hole is clean cut with no sharp edges. Irregularities could cause poor sealing and ultimately leakage. -Insert Uniseal into hole with wide side facing pipe to be inserted. -Make sure that pipe end to be inserted is clean cut. Sand the edges, if necessary. -Using water, lubricate outside of pipe end to be inserted, then push pipe through Uniseal from large flange side. The co-efficient of friction of rubber holds pipe tightly in place. A Uniseal® can even be plumbed into PVC pipe. Uniseal Sizing: 1/2" Uniseal=> 1/2" pipe size=> 0.84"OD=>use 1 1/4" hole saw 3/4" Uniseal=> 3/4" pipe size=> 1.05"OD=>use 1 1/4" hole saw 1" Uniseal=> 1" pipe size=> 1.31"OD=>use 1 3/4" hole saw 1 1/4" Uniseal=> 1 1/4" pipe size=> 1.66"OD=>use 2" hole saw 1 1/2" Uniseal=> 1 1/2" pipe size=> 1.9"OD=>use 2 1/2" hole saw 2" Uniseal=> 2" pipe size=> 2.37"OD=>use 3" hole saw 3" Uniseal=> 3" pipe size=>3.5"OD=>use 4" hole saw 4" Uniseal=> 4" pipe size=> 4.5"OD=>use 5" hole saw 6" Uniseal=> 6" pipe size=> 6.62"OD=>use 7" hole saw