Don't waste the water collected by your greenhouse roof. Halls stop-end and downpipe slot into greenhouse gutter to channel rainfall into a water container. Kit contains one downpipe and therefore two kits are required for collection both sides. This kit is for Halls Popular Greenhouses which are 6ft wide measured at the door end. Halls stopend and downpipe slot into the 40mm greenhouse gutter on your 6ft wide Halls greenhouse to channel rainfall into a water container. Downpipe 35mm.