This ultra-slim, remarkably bright pen light features an LED bulb that lasts up to 100,000 hours and is visible from over a mile away. For hands free lighting, clip it to your cap or clothing. Plus you can easily switch between momentary "blink" and constant "on". The waterproof Stylus is constructed from a virtually indestructible aircraft grade aluminum casing. Perfect for hiking, camping and hunting, it also makes a great bore light. 3 AAAA batteries included.