Black Spiked Brass Knuckles from Knockout Knucks. These are designed like your normal brass knuckles but instead of having a flat knuckle surface, they have 4 sharp spikes on the top. These spiked knuckles have a black stainless steel finish. That means these spiked knuckles won't rust and are pretty much indestructible.  

Complete with 4 sharp spikes on the top. Very nice and solid design.