1. Transparent lock. You can clearly see the working principle of the lock, which is very suitable for locksmiths to conduct training and practice. Its operation is extremely smooth, without any loose parts or locking pins, providing you with a professional usage experience. All moving parts of the lock are equipped with open chambers, so you can clearly see how it works. 2. Features: - Color: Transparent - Material: Metal and plastic - Dimensions: Approximately 5 * 2.3 * 7.9 cm / 2 * 0.9 * 3.1 inches (length * width * height) - Lightweight and durable, convenient for repeated use - Smooth operation, long - lasting, suitable for repeated practice - You can see all the internal structures of a real padlock - It is the best choice for locksmiths to conduct lock training and improve skills, and is also very suitable for beginners 3. Package list: 3 sets of practice locks, transparent training crystal key padlocks specially designed for beginner locksmiths