Hex socket cap screws with UNF thread according to ANSI B18.3 standard. The design corresponds closely to ISO 4762 with a cylindrical head but uses Unified National Fine (UNF) inch threads instead of metric. UNF threads offer finer pitch for improved tightening control, increased thread engagement, and better vibration resistance. The SWEBOLT & BOTNIA BOLT range includes strength classes 8.8 (zinc plated) and 12.9 (plain).