Designed for use on boats wherespace is at a premium. It works using the same principles as the above standard heaters with no difference in performance or efficiency. May be installed both in vertical or horizontal position.Dimensions (L x D mm) - Kg:15L: 505 x 295 - 8Kg20L: 630 x 295 - 9Kg25L: 750 x 295 - 11Kg