Tefen barb connectors are designed to operate with all PE tubes class 2.5-4 PN, at the range. They can work with other flexible plastic and rubber pipes.
The fitting and sealing mechanism is based on a barb that holds the tube from the inside diameter. This is a push fit solution and hose clamps are not required.
Fittings size indicate the nominal outside diameter of the Tube. For example 5/8" barb fitting, fits a 5/8" irrigation tube class 2.5, with inner diameter of 1/2"