General description The 2Pack Security Door Restrictor is designed to enhance the security of your entry doors and windows. With a heavy-duty steel construction, it effectively prevents forced entry while allowing doors to open slightly for identification of callers. This lock is ideal for use in homes, hotels, and storage rooms. Technical specifications Material: Heavy-duty steel Opening allowance: 30-50mm Color: Silver Installation No drilling or chiseling required for installation Usage Provides reliable protection for doors, storage rooms, and windows Cannot be unlocked from the outside once installed