Quality ABS material: the round air vents made of premium quality ABS material, no smells and non-toxic, thickened durable. Build-in screen mesh: to effectively keep bebris, rain from entering the indoor places, also prevent the duct pipe from being blocked. The screen mesh can be dismantled freely, easy to clean and maintain. Slanted louver design: the 45° slanted louver design can make the fresh air flow into your home easily, providing you a better healthy life. Easy to install: bottom diameter 3.74 inch, fitting for 4 inch ducting, can be mounted directly, and fits snugly in the hole or duct using the friction from the black plastic wings. Applications: widely used in kitchen, bathroom, office, grow room, meeting rooms and other places exhaust and ventilation. Also compatible with a 4 inch inline fan ventilation system.