Stage lighting suspension bolts (in certain nations around the world only; some have long gone fully metric, Other folks for example Australia have reverted for the BSW threads, or have never fully transformed): The square thread characteristics flanks that happen to be perpendicular into the screw's axis, creating a 90-degree https://types-of-house-foundation40492.blogchaat.com/29420401/the-basic-principles-of-types-of-screw-heads-torx