The right size depends on the width of your gutter run and the volume of water you need to collect. The Strayton H42A is available in four widths: 305mm (12″), 355mm (14″), 457mm (18″), and 610mm (24″). As a general guide, wider hoppers suit larger roof areas and heavier rainfall zones. If you are unsure, our team can advise based on your gutter profile and catchment area — call 0333 987 4452.