This is the white "Checkey 2" key-forgetting prevention device. ⚠️ Please check the second image or the Miwa Lock official website below for details, as some key types are not compatible. ⚠️ https://www.miwa-lock.co.jp/miwa_smartphone/tec/products/checkey2.html Shipped via anonymous Yu-Packet Post Mini. Instant purchase welcome.