These include, the otoscope, thermometer, stethoscope, penlight, sphygmomanometer, bladder scanner, speculum, and eye charts. A penlight is a small, pen-sized flashlight, often containing two AA batteries or AAA batteries. Due to their popularity in small flashlights, they are often called "penlight batteries". Some types of penlight bulbs or small LEDs have a built-in lens. A penlight should be used to observe the steadiness and positioning of the deviated eye. The soft palate is checked with a penlight.