Casio G-Shock Digital / Analogue Black GA-100-1A1ER Watch. Living up to G-Shock’s reputation for big case designs, comes a revolution in case size with the introduction of the X-Large G. This Ana-Digi, “three-eyed” monster measure in at a whopping 55 x 51.2 x 16.9mm size, with an attention to detail, that is second to none. Large anti-skid buttons provide easy operation, embossed indexes gives a 3-D look and a rivet bezel design adds strength to its overall appearance. Features include: Shock Resistant 200M Water Resistant Anti-Magnetic Structure 1/1000th Second Stopwatch with Speed Indicator Shock Resistant Magnetic Resistant 200 Meter Water Resistant Auto LED Light with Afterglow Full Auto-Calendar (pre-programmed until the year 2099) 12/24 Hour Formats Accuracy: +/- 15 seconds per month Battery: CR1220 Approx. battery life: 2 years Module 5081 This watch comes with a G-Shock authenticity certificate.