This is an ALSOK crime prevention window lock. The "ALSOK" logo faces the window, helping to deter crime. Unopened, unused item. Quoted from an online shopping site: Comprehensive Security ALSOK Lock Size (approx.): Width 8.2 x Depth 0.9 x Height 6 cm A gap of 10mm or more is required from the outer sliding glass door surface to the inner sliding door's vertical frame. Easy to install! Can be installed on patterned glass. The ALSOK mark deters intruders!! This is an auxiliary lock that is installed from the inside on the sliding aluminum sash windows of your home. Auxiliary locks are effective in delaying a crime when glass is broken (breaking the glass near the crescent lock and reaching in to open it). It can be easily attached with adhesive stickers directly to the glass surface. There are two lock plates, and by locking only one, you can lock the window while leaving it open a few centimeters for ventilation. From the outside, the "ALSOK mark" printed on the adhesive surface of the auxiliary lock is visible, which is expected to deter crime. ・Cannot be used on frosted glass. ・This product does not completely prevent intrusion. ・The color of the product may appear different from the actual color depending on your monitor, so please understand.