National Nail Structural Screws 6" x 1/4" 250 Pk1 4 in. (6. 35mm) structural screw for deck substructure, deck posts, beams, handrails, landscape timbers, and more Replaces 3 8 in. (9. 53mm) lag screws Sharp point starts fast with no pre drilling Flat, washer style head provides stronger holding power and greater surface contact and finishes flush 3rd party tested for screw strength confirmation T 30 and T 40 Star Drive provides more points of contact, reducing cam outs and limiting bit wear