คุณลักษณะ

• It has a thin, compact and simple design that you won't recognize as a whistle.
• The small size of 48 x 23 mm makes it comfortable to wear.
• Since the sound comes out at a frequency that is easy for people to hear, the sound reaches far and is easy to hear.
• It is suitable for field workers who always use a helmet.
• A chin strap that can be replaced with an existing helmet.
• It can be used as a normal buckle normally and as a whistle in an emergency.