Two Finger Knuckle Duster DFK 03 Carbon Fiber

Dimensions:
Material - Carbon Fiber
Color - Black
Height - 2 11/64" (55 mm) 
Width - 2 13/32" (61 mm) 
Thickness - 43/64" (17 mm) 
Finger hole diameter - 1" (25 mm)
Weight - 1.5 oz / 45 grams

Special holes allow you to use this product as a Keychain. 
You can also thread a paracord (550-type) lanyard through the holes.
Nice gift for Him.