This is a highly reliable auxiliary lock, designed to be installed on the inside of aluminum sash windows and featuring a sticker from CSP Central Security (related company). - Product Name: Lock Ban - Features: Designed for effective crime prevention - Material: Body and rails made of rust-resistant stainless steel (SUS304) - Installation Width: Can be installed with a gap of 2mm or more - Applicable Size: Compatible with window thicknesses up to approximately 8cm - Design: Simple and functional design ※ Includes two "Crime Prevention Measures in Progress" stickers from CSP Central Security. I purchased this for my home, but it didn't fit my windows. It has been stored at home unused, so please refrain from purchasing if you are concerned. Thank you for looking.