Special Delivery. Your students will love sorting pictures, colors, shapes, letters, sounds, names, numbers, anything with these realistic, durable plastic mailboxes. Big openings allow them to pull the door open and " mail" objects as well as cards and letters. Let go of the sturdy, spring-loaded flap doors and they close all by themselves, just like real mailboxes. Bottoms slide open for convenient removal of the day's mail. Mailboxes measure 6 1/2" H x 3" W x 2 1/4" D. Set of 6.