Opoway Nurse LED Penlight with Pupil Gauge, Warm White with Batteries, Pack of 2 This LED penlight produces a Warm White LED light, perfect to check areas of the mouth and throat as well as examine wounds. Light weight and portable, with high quality aluminum alloy body and built in metal pocket clips, make it durable and easy to carry. The penlight medical are also built in pupil gauge and 5cm ruler to help determine the size of a patient's pupil when doing a neuro assessment. The reusable penlight with 4 AAA batteries included (2 per penlight), so you don't have to go searching for some little battery cells, very convenient. The push button on top to turn it on makes it easier to use, don't have to continue to depress the side clip like others.