• DIN : 86
• ISO : 7380
• DIAMETER : M-1 TO M-6
• THREAD :Metric , Inches

Round head bolts (button head) are commonly used in wood connections. Round head bolts are similar to carriage bolts, but without the square neck under the head. Because they are used with wood, round head bolts are rarely high strength and virtually always supplied in a standard ASTM A307 specification.

What is the difference between pan head and round head screw?
Pan heads are similar to round heads, truss heads, and binding heads, although pan heads have largely replaced these other heads in modern screws. Round-head screws have a domed head and a small bearing surface, applications using round heads demand a high level of aesthetics. .