... "-4" Shank:smooth,longitudinal,twisted groove Color box Straight Shank K Type Head Concrete NailConcrete and masonry nail are hardened wire nail ... , twisted groove, angular spiralHead: headless,flat head,countersunk head,K type,T type,etc.Popular Size: galvanized steel concrete nail1.8×20mm4.2 ... and roofing nail are also available for customer ! Straight Shank K Type Head Concrete Nail