Countersunk hex socket screw according to ANSI B18.3 standard with UNF inch thread, plain (uncoated) steel. The UNF fine thread provides more engaged threads per unit length, resulting in better load distribution and more precise tightening. Used in imported equipment, process installations and applications requiring fine thread control and a flush fit. The plain surface is suitable for dry environments or assemblies that will be surface-treated after installation. Available in multiple sizes from SWEBOLT & BOTNIA BOLT.