Sherline Trailer Tongue Weight Scale --- Used to determine the trailer tongue weight and ratio of tongue to total trailer weight. To achieve the maximum ouput of our TrailerTug machines, we recommend at least 10-15% of the total trailer weight on the hitch. Note: A 8000lb trailer should have 800-1200lbs on the trailer tongue. Avoid overloading your trailer tongue—position it directly on the scale to determine the weight. A removable 2 1/4" long extension supports the tongue in the ball socket. Use the first time you load any trailer and every time the load changes. Scales convert weight into a direct reading on a hydraulic pressure gauge. The reading (in psi) is equivalent to the tongue weight in pounds. Body is red anodized aluminum; piston is steel with black-oxide finish. Gauge has a plastic lens.