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). 1inch to 3/4inch hose joiner - for permanent connection of two different sizes hoses. 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