Ryobi's No. 3 Spiral Screw Extractor is the best choice to remove those stubborn 5/16 in. to 7/16 in. screws and bolts. Simply use a 5/32 in. drill bit to drill into the screw or bolt. Tap the spiral screw extractor into the fastener and use a wrench to assist in twisting the extractor till the fastener is removed.