Cast iron pump outlet body and handle (except 1293) provide durability and longevity. Metered models have air expeller built into pump tube (prevents air from registering on meter). Large replaceable swivel casters provide ease of maneuverability (mobile models). Baked enamel finish helps prevent rust and corrosion. Self contained units and sealed models prevent contamination or spillage of product being dispensed. Smooth, easy pumping action (no crank or gears) dispenses all types of gear lubricants, even in the coldest weather. Volume @ Stroke is based on using 90 SAE at 70º F.