Window lock with a key and a double safety mechanism, compatible with installation widths of 30-45mm. - Product Name: Window Lock Zero - Installable Width: 30-45mm - Features: With key, double safety mechanism Thank you for looking. I purchased these to prevent my child from running out, and the two on the right are unused. There are four locks as shown in the photo. I intentionally disposed of the black keys to keep them from being found by my son, so there is only one key. I'd like to sell these to anyone who is interested.