These sturdy, low-profile hatches open from the inside for added security. Molded of durable, corrosion-proof high-impact ABS plastic with 3/4 inch (2cm) smoke acrylic lenses. They give a professionally finished look with snag-resistant radiused corners, hidden fasteners and interior latch dogs and trim rings. A rubber gasket creates a watertight seal. Noncorroding plastic hinges open the hatch to 90 degree. A twist-lock riser arm locks the open hatch in place anywhere from 0 degree to 90 degree.