This item has have high-middle-lower sensitivity selection with 4 digital code, only the user can unlock. It can protect the bike lock from destroyed and prevent the behavior of moving the bicycles by the thief. and also have the functions that the anti-theft lock can not substitute. Features - Color: Black. - Size: Approx. 9.7 * 6.2 * 3.7cm/ 3.8 * 2.4 * 1.5 inch (L*W*H). - 4 digital code, only the user can unlock. - Quiver-style alarm, 110dB high export sound. - Have high-middle-lower sensitivity selection. - Protect the bike lock from destroyed and prevent the behavior of moving the bicycles by the thief. - Have the functions that the anti-theft lock can not substitute. - Code switch, convenient to use, avoid key switch weakness which easy to open with other key. - Low power consumption to allow the battery a long life. - Waterproof: Attach permanently to your bike without worrying about having to remove it in bad weather. - Easy DIY installation.