Purpose of the Device: The HPF device is used to measure the force exerted on the driver’s head during vehicle roof strength testing. Applicable Standard: U.S. Federal Motor Vehicle Safety Standards (FMVSS), Section 216a: Test Method for Roof Crush Resistance. Headform Mass: 6.8 kg. Headform Diameter: 165 mm (hemispherical rigid model); remove four dummy torso weights (two on each side) during loading.