G-Shock Watch Alarm Carbon Core Guard Mens GA-2100-1A1ER. This stealthy, all black timepiece embeds the latest carbon core guard technology in a slimmer more refined case. Taking inspiration from the 1983 original model, the DW-5000C, this watch gives homage to the much loved retro look with its unique octagonal bezel, framing an analog-digital display. As with the GA-2000, the GA-2100 has an interchangeable resin strap for customisation with any outfit and occasion. Despite its deceptively compact design, this watch is as durable and tough as any G-SHOCK on offer with 200 meter water resistance and shock resistance.