Check the listing for details. 1/2 Inch (10-Pack) Flexible Tank Adapter, Pipe to tank Seal Fitting, Premium. Condition: New. Listed at 23.80 USD. Pipe-Tank flexible tank adapters made of Thermoplastic Vulcanizate (TPV), commonly used in plumbing and aquaponics system and are designed to create a watertight seal around pipes or tubing passing through a container or surface. Installing the seal is easy. All you need to do is cut a hole with holesaw into container surface and insert the seal, coating the pipe with a slippery soap water and push it into the seal. The pipe squeezes through and form a liquid tight seal. The TPV consists of a mixture of polypropylene plastic and EPDM rubber. During the step of combining them, though, the manufacturer vulcanized the rubber, which gives it a strong mixture of compression and heat resistance. TPV is offering a higher level of elasticity than EPDM itself. Some advantage of TPV compound is resistant to most acids and oils, maintains its integrity in low temperatures, resistant to UV.