These patio door locks are designed to lock a sliding door into closed or ventilating position, and they operate with a simple insertion of their pins into a retaining ring to help prevent unwanted sliding of a door panel. Each lock is constructed of hardened steel pins that protrude past the inner door panel and extend into the secondary panel to lock an active door into place. A pin holder bracket is also included for easy storage when not in use. These locks help to prevent prying and lifting of the active panels, significantly reducing the chances of entry from the outside, and they can also be used on both vertical and horizontal sliding windows. Installation hardware and instructions are included, and they can be installed with a few simple tools.