Use for connecting lengths of 13mm Internal Diameter LDPE pipe and dripline. Fits 13mm internal diameter (ID), 16mm (OD) LDPE Pipe. Antelco 13mm Barbed Tee Connectors: LDPE Connectors, Barbed Fittings. Drip irrigation barbed Fittings are used to make connections between 13mm drip irrigation or LDPE pipe. Fits pipe with 13mm Internal Diameter (16mm external).