Think of the inward block as a hammerfist at the inbound puch, striking with the inside of the forearm about 1.5-2" below the wristbone, at no more than a 45 degree angle (I prefer 30 degrees), while stepping into a fighting horse for maximum hip rotation. It begins by cocking the fist by your ear with your palm facing your attacker and (as you shift into the fighting stance) it extends out rotating clockwise until your palm faces you. The primary target is your opponent's radial nerve.