#6 x 1/2" Stainless Steel Wood Screws Flat Head Slotted Countersunk Qty 50 These Slotted flat wood screws are a 18-8 stainless steel with rolled threads. Rolled threads have a constant shank diameter that tapers at the point. Wood Screws are a thread forming screw with a coarse pitch thread. Flat Heads are countersunk allowing the fastener to sit flush into the wood surface they are screwed into.