The rear of inserts is always sealed to prevent cement water entering the socket. Because of their form the products are unsuitable for thermal zinc plating. With connectors 1550/1551 which are open on both sides this is irrelevant. These connectors can be supplied hot dip galvanised and are also applied with bolt anchors 1988 and bar anchors 3010.

The basis of CUR 25 is a clear anchoring length. This cannot always be clear indicated with inserts. Furthermore, most inserts do not meet the requirements made in CUR 25 as regards dimensions.

So one cannot use CUR 25 as a method of calculation for inserts.