Product Material: Nylon Size: 17*11.5 cm Color: Black Package Content: 1 pcs training alerter 1. Application: With the sound from this golf training aid, golfers can detect left arm curvature errors to help maintain a straight left arm position, promoting a more effective and consistent swing. Suitable for all golfers and golf training sessions, especially beginners. 2. Sound alerts incorrect posture: The golf swing trainer features an integrated alarm mechanism made from special material that emits a sound when the elbow bends during a swing. This alerts the user to incorrect posture, prompting adjustment to keep the left arm straight. 3. Adjustable and portable design: Strong Velcro and buckle allow for easy adjustment, secure fit, and simple on and off use. The thick plastic buckle is designed to avoid skin irritation, unlike thin metal buckles, and fits most arm sizes. 4. Secure fit with enhanced feedback: Unlike basic belt-style trainers, this device wraps fully around the elbow area, minimizing movement during use and providing more reliable feedback to the golfer. 5. Breathable and comfortable material: Made from high-quality breathable nylon fabric, webbing, and Velcro fastener, this training aid is lightweight, durable, and designed for comfort during extended use.