Economy Push-Pull Force Gauges. These high impact polystyrene cased Push-Pull Force Gauges are low priced and simplified in construction yet accurately measure push pull forces. The GPP Push-Pull Force Gauge is graduated in two scales: grams and ounces. Ideal for field service use and applications requiring gauges with maintenance free operation. Precision springs individually are calibrated and checked with dead weights. Full scale accuracy and permanent calibration is held to ± 1 graduation.