Designed to protect seedlings and accelerate early , Blue-X Tree Shelters feature patented two-piece construction and create a beneficial microclimate to aid in seedling survival. Each tree shelter is comprised of a single sheet of blue plastic film which is inserted into a blue-tinted poly sleeve. The blue film produces amplified blue light to increase beneficial photosynthetically active radiation and boost tree diameter . In addition, the tree shelters block a significant amount of harmful UV light which can damage DNA and hinder . The poly sleeve can be removed when the tree shelter is no longer needed, and the plastic film can be stored for reuse. Each tree shelter measures 3-1/2" in diameter and has an outdoor life of 5 years. Price per 100 shelters. Stakes sold separately.