Measures: About 15cm long. Hidden room measures: About 8cm x 2.5cm diameter. The default password is I LOVE U. You can also set your own password. The password between you and your friends is not open when he is wrong. So it's interesting. You can contact us to set your password. Beautiful packaging, you can see the picture, I believe you will like it When you open the lock, you can see two rings, and I'm sure you'll be surprised at what you care about. Of course, you can also buy, in which more precious rings or necklaces, and so on. When you set up a new password, just turn the screw and re edit the alphabet 6 password ring. The Da Vince code Mini Cryptex, Christmas and Halloween are the most interesting gifts for friends, children and parents. Of course, Valentine's Day gives the best gift to others. If you have any questions, Beautiful packaging, you can understand through the picture, I believe you will like it When you open the lock, you can see two rings, and I'm sure you'll be surprised. Have a great time shopping!