Inch 4#-40UNC 304 Stainless Steel Allen Socket Cap Head,Button Head,Sunk Head Screw Bolt,Nut,washer Product Attributes: Material: 304 Stainless Steel Drive :Allen Head type:Socket Cap Head,Button Head,Sunk Head Thread Size: 4#-40UNC Thread Count (TPI) :40 System :Inch system Length length is optional