About A307|ASTM A307 covers low-carbon steel externally and internally threaded standard fasteners. Grade A is the basic bolt for general, non-critical applications. This is the cheapest structural bolt, essentially
A36 steel in bolt form. Used for wood connections, light structural joints, and non-critical fastenings where A325 or A490 high-strength bolts aren't required. Compare to A325 (high-strength structural bolt, much stronger) and A36 (same type of steel, different product form).