Rule In-Line Bilge Blower For 4 Ducting The Rule In-Line Bilge Blowers are designed for efficient, high output operation. Each Rule In-Line Bilge Blower features their exclusive front and rear shaft seals and corrosion resistant motor housings for long life. Although these bilge blowers are compact, they provide higher air flow, lower amp draw, and quieter operation than standard blowers. Easily installed on any flat surface. Efficient high-volume air flow Quiet operation Low amp draw Slip-on in