Material: penlights are made of premium aluminum alloy body and high quality led bulb, Design: Top with push button on/off switches, easy to control, Convenient: Metal pocket clip,lightweight and portable,easily fits in your pocket, Compact & Portable: This penlight is 5.3 inches long, powered by 2 pieces AAA batteries(not included), Professional & Efficiently: Penlight with pupil gauge and ruler chart on both side of pen light are very useful for your measure the pupil size and bodies of patient's,