This item is a part of 1" heavy duty hose connection system which is designed to work mainly with 3/4" and 1" hoses. The quick connection fittings are bigger than standard hozelock compatible domestic connection and are 26mm in diameter (please see the picture). To connect 1" quick connection to standard 1/2" or 3/4" hozelock size. This item is a part of 1" heavy duty hose connection system The quick connection fittings are bigger than standard hozelock compatible domestic connection Quick connection diameter: 26mm