This medium sized mail slot is made of 1/4" thick cast brass. Handcrafted with the word "MAIL" cast into the flap. The mail flap pushes in to insert mail and is closed by gravity. Designed with a textured surface and available in brass, chrome or antique finish. Includes an adjustable stop that can limit the size of the mail flap opening. Heavy duty tamper proof brass bolts secure the front and back frames to each other from the rear and accommodate solid doors and walls from 1 1/4" to 1 7/8" thick.Dimensions. Exterior and interior face plates: 13 1/4" W x 3 1/2" H. Opening in plate: 9 1/2" W x 1 3/4" H.