This Supersub Smart 650 bilge pump is uniquely designed for narrow bilges. Is able to go where others cannot, ensuring that the pump can access water deep down in the bilge of the boat or difficult to reach areas under engines or in personal watercraft. It's high flow rate, and innovative technology place this pump in a class of it's own. The pump measures 2 1/8" high by 2 15/16" wide. The unique dimensions make this pump the lowest profile, automatic bilge pump on the market and the high 650 gallons per minute flow rate on such a compact pump is almost unheard of. It utilizes Whale's patented electric field sensor technology which senses the water level and automatically controls the pump, making it fully automatic.