The hanging rail is a 40mm diameter aluminium tube, powder coated to the same colour as your Greenhouse and fitted to the roof using stainless steel brackets and bolts. It is used for hanging hanging baskets or tying climbing plants up to. The length shown is not the actual length of the Hanging Rail but the length of the Janssen Greenhouse side or gable it will fit into, the Rail is a little shorter. We stock the Rail in standard colours of Black, Green and White, but if you are ordering a Greenhouse from us in any other colour the Rail will be supplied to match it (unless you wish otherwise).