5 1/8 overall. Grooved aircraft grade aluminum body with anodized finish, crowned bezel, and tail cap push-button switch. Water resistant up to 1m. Three modes: momentary, on, and strobe. Ultra Bright white LED with up to 320 lumen output. Visible up to 193m. Requires two CR123 batteries (included). Up to 4 hour run time on high and up to 17 hour run time on low. Hang packaged.