These seedling protectors are a flat sheet (slit tube design) that is formed into a "tree tube" with the releasable zip ties that are included. The tubes are 100% recycled polyethylene (milk jug plastic), UV stabilized for 5 to 7 years. They have a single-wall design with a seam down one side, and a tab-flared top to protect seedling from sharp edges. Tube diameter is 4.15" (allows connecting multiple protectors for larger diameter) with vents starting halfway up to allow herbicide spray around the base. Cost per 4-foot tree protector includes one treated stake and ties.