For moving small dinghies across sand or beaches Etc. At least 2 rollers should be used, depending on the type, length and weight of the boat. 2 models are available that are suitable for a range of dinghies and small craft to a maximum of either 200Kg or 450 Kg weight when fully laden including all onboard articles and outboard motor, if applicable. Inflate with a small air compressor. Medium Duty - Heavier duty vinyl material 450 Kg maximum weight. 1.25 metres x 250mm when inflated