Speaking from Xenith’s test lab, Ron Jadischke says: ‘We have a few different pieces of impact-test equipment. We regularly use a couple of drop towers, as part of the ongoing quality-control and developmental testing. There’s a head form, representative of an average adult male, that’s mounted to a carriage and connected to the drop-tower mechanism, all pneumatically controlled. We'll bring the drop tower in the head form up to its height and, once it’s reached its height, dictating the speed it’s going to fall at, let go of the carriage, which falls and impacts the flat pad below.’ Demonstrating this, he says: ‘That would have been simulating the highest speed drop tests that we would do, about 18 feet per second, which is a pretty severe impact, roughly five and a half meters per second to do the conversion.’ The pass-fail criteria is a different metric to Gs, called severity index, an injury bio-mechanics metric that originated at Wayne State University, Detroit.