The Tassalini 1.5″ sample valve & assembly can be installed on the 26, 80, 240 or 300 gallon units. Almost all buyers opt for this, and those that do not usually order them later once they realize the convenience factor drawing a sample without disturbing the lid. When ordered from us, we install the sampling valve. Unfortunately, we cannot warranty sampling valves against leakage where a customer drilled the required hole in the tank. That said, such a process is relatively easy to perform.