Quick answer: This is a dive computer from Seac.
A dive computer tracks your depth, time and no-decompression limits so you can dive with more confidence. For bigger divers, check the strap length: it needs to close comfortably over your thickest exposure suit, or you'll want an extension.
Offered in 3 options, including Black/White, Black/Red, Black/Blue.
Read the manual so you know the display, units and alarms before diving, and check the strap length against your wrist over your exposure suit. Read Best Dive Computer Watch for Beginners. More options: Dive Computers for Larger Divers.