Every bicycle needs a lock to keep it safe. However, a lock does not help to find your own bike on a crowded parking lot where there are usually hundreds of bicycles. Poor lighting sometimes makes finding your bike even harder. This acoustic-optical lock system uses a radio transmitter in the key and a radio receiver in the lock. When the button is pressed, the lock makes a sound and emits a light, making it easy to locate the bike. This is designed to make life a little easier for people who want to enjoy a low-carbon lifestyle.