GROZ 45641 Mechanical Diesel Meter (Gallons) , 1" NPT (F). High Accuracy Diesel Meter with mechanical register, Nutating Disc mechanism offers high tolerance to fuel contamination Meter is designed for both In-Line applications & gravity flow (with a minimum gravity head of 4'), Ideal for use with Electric Fuel pumps Register cap can be easily removed & rotated to every 90° orientation for display reading, Robust Aluminum Die Cast construction Easy user re-calibration, Works with both Fuels & Oils. RECOMMENDED USE Diesel, Biodiesel, Low to Medium Viscosity Oils; DO NOT USE WITH Gasoline, Water based media;