1/4-20 Hex Head Bolt, 18-8 stainless steel. USS Coarse thread. Hex head is 7/16" across the flats. Very good corrosion resistance. These are good for applications where they will be used outside.
304 Series Stainless Steel, (18-8)
Tensile - 100,000 psi to 125,000 psi, Hardness - 85 Rockwell B
1/4-20 USS Coarse Thread
Great corrosion resistance for outside applications