2 Finger Brass Knuckles DFK 03 Black Anodizing Type 3

Dimensions:
Material - Aerospace Aluminum
Coating - Sand Blasting / Black Hard Anodizing
Height - 2 13/64’’ (56 mm) 
Width - 2 13/32’’ (61 mm)
Thickness - 43/64" (17 mm) 
Finger hole diameter - 1" (25 mm) 
Weight - 3 oz / 90 grams

More similar products you can find here:
cheap aerospace aluminum edc knucks buy online in the USA

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.

EDCCraftStore official website is the best place to buy original EDC-products at manufacturer's price.