Mini Valve Spring Tester: The Mini Style Valve Spring Tester is a quick and easy way to check your valve spring. It can be used in a vise or an arbor press. Reads up to 300 pounds in 5 pound increments. A must-have item when rebuilding cylinder heads, upgrading camshaft, or when doing any valvetrain work. Interchangeable Manufacturer Part Number: 66835. Measurement: Spring Pressure Range is 0-300 lbs./in. 5LB Increments. Valve Spring Tester Style is Mini for vise / arbor. Complete with a Rubber Gauge Protector. Replace P/N: 66835. Superior Material: .