TreePad is a great way to protect your slings and tree bark from abrasion. Simple yet functional design alows universal usage. With 200cm length and 12cm width, TreePad is sufficient for most of common trees or other anchor points (maximum 60 cm in diameter). You can attach more pieces of TreePad together with velcros which comes in handy during bigger longline or highline projects. 
The velcros are also used to fix the anchoring sling in place before tensioning the line which makes life so much easier. At least while rigging a slackline :) The kit includes 2 pieces of TreePad.