The ideal solution for applications that use adhesives is not possible or desired. Suitable for repetitive use. Also when the tube connection is not exactly "angled" or right fit these fittings. In the summary table shows these links are appropriate for which external measurements: external tube size, but also the outside measurements of PVC fittings! Material: PVC elastomer. PVC Elastomer has a very strong tensile and tear strength, is very flexible and not subject to ageing ("verrubberen").