25 mm Uniseal.
A Aquaseal, also known as a Uniseal is used to create a water tight seal around the circunference of a pipe going through a hole on a tank or aquarium.
Uniseal is also available in the following diameters:
Posted by Unknown on 28th Feb 2019
Seals work great, one had a few drips but after adjustment works perfectly.
Posted by Heinvr on 11th Sep 2014
The AquaSeal, though costly does precisely what it was designed to do. It can take serious punishment form first time users and so far they (4) have not leaked a drop. A good product that I would recommend and use again.