Graco Fire-Ball® 300 Series 50:1 400 lb. (181 kg) Grease Pump Package Stationary Supply Package Non Agitated (Standard) The difference between the two

The difference between the two is that the #4 allows for more fluid output

Fuji 1000cc Gravity Cup Mount is designed for the center-mounted T-Series Gravity Gun

Fluid injection is caused by the high pressure  fluid piercing your skin

For example to replace the 1

Graco Fire-Ball® 300 Series 50:1 400 lb. (181 kg) Grease Pump Package Stationary Supply Package Non Agitated (Standard) The difference between the twoAs the mainstay pump in the industry for decades, the reputation of Fire Ball is unrivaled. Built to withstand the test of time with fewer moving parts, our flagship pump is built to extend uptime so customers can be more productive. The durable pumps are renowned for their durability, with pumps built decades ago still operating efficiently. Install the Fire Ball 300 50: 1 in grease dispense applications. Reliable Flow A 3 inch (76. 2 mm)