Answer
Dec 10, 2025 - 09:44 AM
The #4-40 x 3/8 BHSC xxxx included in the polarstar kythera set is a #4 gauge xxxx with a 40 threads-per-inch count and is 3/8 inch long with a Button Head Socket Cap (BHSC) design. The BHSC head allows for a flush finish and provides a larger contact area, which is ideal for airsoft components needing secure fastening.
