one thing I notice is a lot of people attach their system to the tree at the seat level. if you attach it as high as you can reach, and you should fall it will catch you in a shorter distance, therefore eliminating injuries from the system. remember that the weight of a falling object (and stopping force) is greater as the distance of fall increases. Another issue is people building their own system with carabiners you get at walmart. Those are for utility use only and are not rated for life safety usage. I personally orderd life safety rope and locking carabiners that are NFPA certified . to make my system.