Tactical, Professional, High Performance in 40 mm case size... The A-2S Ballista features professional tactical design in a durable 40 mm stainless steel case. All stainless steel components... case, crown, case back, band hardware... all are ION (or PVD) coated non reflective matte black. High performance components built into the A-2S Ballista include: A rugged screw down crown & case back, 200 M water resistance rating, scratch resistant hardened sapphire crystal, Swiss super luminous numbers, markers & hands, precision all-metal movement, functional easy to read dial with 12/24 hour markings, and date sub dial.