This Is The Small Size (Mini) Wedgit Security Bar For Single Hung Or Sliding Windows Or As A Sliding Glass Door Lock If You Are Using A Pet Door Panel. I Also Have A Large Size (Maxi) To Use As A Sliding Glass Door Lock Without A Pet Door Panel. Please Check My Other Listing. This Lock Twists The Door Or Window Into The Frame For A More Secure, Efficient Weather Tight Seal. This Is Not Only Great For Added Security But It Also Helps Childproof Your Sliding Glass Doors And Windows.