Key Locking Book Safe. The locking book safe looks like an English Dictionary on the book shelf. However it has a Key lock and has plenty of room inside for a small pistol, cash, jewelry, credit cards and much more. Comes with two keys. The interior dimensions of the safe are 6 3/4″ x 4″ x 1 3/4″. The outer dimensions are 7″ x 4 1/2″ x 2 1/8″.