1. Made of excellent quality engineering plastic by injection molding, higher density and more firmly\
2. With UV resistant additive, air inlet has stronger anti-aging ability, longer service life, better sealing, flexible opening, with anti-bird nets.
3. With two pulleys design, easy opening, reduce friction, strengthen rope service life.
4. Air inlet door uses the pulley device firstly device firstly to reduce friction and strengthen the rope's service life
5. Air guide plate for option which efficiently control the air direction. If need it, please notice