Pen Light, Zitrades Nurse Led Medical Penlight with Pupil Gauge for Nursing Students Doctors with AAA Batteries (Red/Silver-11) Five buttons occupy a simulation port and save more resources Analog variables acquisition, press different keys and output different voltage Adopt high quality omron buttons, sensitive and durable Standard interface that can be expanded in a variety of development boards Applicable to a variety of platforms including Arduino / AVR / ARM