Military Standard Aircraft Machine Bolt
- Hexagon head
- Undrilled head
- No cotter pin hole
- Fine threads
- UNF-3A
- Material: Steel
- Major diameter: 0.3125 inches
- Thread per inch (TPI): 24
- Length: 4.094 inches
- Grip Length: 3.563 inches
- Industry standard specification: AIA/NAS NASM3-20