Speeds drain down of radiators, preventing stains on carpets. Snap clip holds tub in position on 10, 15, 22mm pipe sizes. Angled fastener guides water to tub. Flexible so can be compressed to fit under low hung radiators. Plumb Tub. The Plumbtub is bendy and flexible, meaning it can be used at many different angles, also aids the speeds of draining down of radiators, preventing stains on carpets. Holds 1.4 litres of water. Fits 10mm, 15mm 22mm Pipes.