Screws were described as "2BA", "4BA" etc. 2BA threads are commonly found in the old imperial BESA conduit boxes. BA sizes were also used extensively in aircraft, especially those manufactured in the United Kingdom.
2BA Brass Slotted Raised Countersunk Screws - Instrument Head Screws - 1/2" / 1"
2BA Slotted Machine Screws BZP (CSK/R/CSK/CHEESE HEAD/ROUND HEAD/MUSHROOM HEAD)
Vintage 2BA Slotted Hex Nut x 5
SOLID BRASS SLOTTED COUNTERSUNK WOOD SCREWS ALL GAUGES & SIZES 2,3,4,6,8,10,12
No4 No6 No8 No10,12,14 Stainless Raised Countersunk Slotted Self Tapping Screws
STAINLESS RAISED COUNTERSUNK SLOTTED SELF TAPPING SCREWS No4 No6 No8 No10,12,14
