This pocket sized thermometer reads in degrees Fahrenheit by simply pushing a button on its face. Holding the button down provides continuous readings. It comes with a replaceable CR2032 Lithium Button Cell Battery for long life. It has a loop in the case for attaching it to a key chain or tool ring. Dimensions: 3.57" x 1.42" x 0.52 (9.0cm x 3.6cm x 1.32 cm) Temperature Range: -27F to 390F.