When selecting a professional-grade electric grease gun, prioritize the maximum operating pressure, which should ideally reach 8,000 to 10,000 PSI to clear clogged fittings. Evaluate the flow rate (measured in ounces per minute); high-efficiency models typically offer 5.0 to 7.0 oz/min. Additionally, check the battery platform—lithium-ion batteries (18V or 20V) are the industry standard, providing longer runtime and consistent power compared to older NiCd versions. Ensure the unit features a variable speed trigger for precise flow control.