Important Note: The diameter of the bottle mouth should be between 26mm to 28mm, or it wont fit. As a Combination Lock, Leak-proof locking cap, Secure your wine at home restaurant or other places, keeps your alcohol safe and untouchable from your kids. Great for preventing children, teens or roommates drinking your booze, Lock in your three-digit combination(keys free) and keep the contents in your bottle safe and secure. Also can be used as a bottle stopper and wine preserve, multifuctional. Password setting method: Step 1: Press and hold the silver round button on top; Step 2: Adjust the number on top( initial password: 000) to a new password you want to set; Step 3: Release the button,password setting will be finished. Fits most wine and beer bottles as well as some liquor bottles, but please refer to the dimensions first. As a Perfect Gift - Cool and useful gadget, your friends will love this little gift from you.