I use a noose to attach it to the top of the tree then I use a taut line knot at the bottom of the tree. Don't buy the system from Summit it will cost you much more. Go to a climbing store and buy the rope. The prussic knot just needs to be a smaller diameter rope than the main run rope. I use 11mm for the main run and 9mm for the prussic with a 5 newton ton carribeaner (sp)

It is a great system. I've bought enough rope to make two of them for less than the cost of the summit system.

Tom