The inside dimensions of the box are 6 wide x 6 deep x 7″ high. The slot size is 3 long x 3/8 wide. The sign holder on the front of this box is 6.5 wide x 7.5 high. It has a hinged lid with a hasp and padlock and is made of 1/8″ acrylic. It can be either wall mounted or set on a counter. Colored boxes still have a clear sign holder in front where the sign inserts.