Several years ago a friend and co-worker at an engineering firm went to a demonstration of a similar piece of equipment to be used for clearing property lines. He was standing with a group of people about 75 feet behind the equipment as it operated when the machine threw a 4" diameter 'log' like an arrow from a bow, that struck him in the chest. He spent two weeks in the ICU but survived to retire with a nice nest egg from the sponsor of the demonstration. This is an amazing machine, but don't get too close!