Pen Light, Escolite LED Penlight Medical with Pupil Guage for Doctors Nurses White Blue and Black UPDATE: it not just a penlight but also a Stylus Pens. Sensitive, smooth use on any screens of digital products, responsive as finger touch. Protects screen against fingerprints, grease, scratches, and other damage. For Nurse and Doctors: Are you a doctor or nurse? the warm white light is perfect and safe to check patient pupil. if you work long nights, have some patient sleeping that you need to check on? this nurse penlight is a great tool to check on your patients without turning on the lights unnecessarily. Good Design: handy and extremely lightweight, easy to carry around, fitting right in the your pocket, lab coat, bag or in your book. and the clip can ensures it won't fall out. Good quick reference on the side, the pupil marker is very helpful for comparison. Multi-function (Daily life necessary): Everyone need a penlight at hand, to light the road when you need walk at night, a pen beside bed in case Power outages. also can be home use such as do eyes, throats, ears, throat exams. LONG LIFE: the battery life is dependable. It uses a single LED & 2AAA alkaline batteries that can be obtained cheap from many sources. the nurse penlight come with 4AAA battery for you to change.