Generic 50 Ft Air Water Vinyl Tubing [1 4" ID x 3 8" OD] (55 270 1511) vacuumrelease An adapter like this is An adapter like this is useful because it creates a cleaner transition between two different plumbing formats while preserving the serviceable nature of the union side of the assembly The UHXNEGVT13501 is a practical venting component for compatible Hayward Universal H350FD heaters that need renewed negative pressure indoor vent support The 1 4 inch inside diameter gives this tubing practical value because smaller control or service lines often need compact tubing that still remains flexible and manageable When smaller flexible runs are needed