Convenient to use: these reusable nursing penlights are push-button on/off switches with pocket clip. It is easy to control and place them on your uniform pocket. Lightweight and Convenient: these pen lights are light and compact, convenient to carry anywhere. These Pen lights are made of premium aluminum alloy and led bulb, which make sure these nurse penlights durable and long-life using. There are pupil gauge and a 5 cm ruler on the side of the penlight. It is very helpful for you to measure the pupil dilation and length on using these medical penlights. Note: This product is powered by two AAA batteries. Batteries are NOT included in this product. Size: 1.28*12.5 CM / 0.5*5 inch Powered By: 2*AAA Batteries Material: Alloy + LED Bulb Color: Black / Silver Package Included: 1/2 PCS Of Nursing Pencils