This cash box can be used as a piggy bank with coins slot on the top, ATM saving box, paper notes automatically winding from the front, and it will play nice music when you transfer money. You need to set a 4-digit code to open the door, the preset code is 0000. Enter the correct password and then the light will turn green (the wrong code will turn red), then rotate the knob clockwise to open the door. Use this small safe box to protect your personal items and paper money. Smart Electronic Money Safe Money Piggy Bank Lock for Coins/Notes Safe with Locker Key is to guard your personal items.