Rule In-Line Blower 4". They feature our exclusive front and rear shaft seals and corrosion resistant motor housings for long life. Compact and easily installed on any flat surface Rule In-Line Bilge Blowers provide higher air flow lower amp draw and quieter operation than standard blowers. This In-Line Bilge Blower has 4" ducting (102mm) 12 VDC and requires a 4A fuse size. Specifications for Rule 4" In-Line Blower: Manufacturer: Rule Color: Black Voltage: 13.6 volts Features of Rule 4" In-Line Blower Ducting: 4" Open Flow (CFM): 235 Volts: 13.6 Package Contents: Rule 4" In-Line Blower Rule 240: In-Line Blower 4"