3b thread class right-hand 28 thread quantity per inch double hexagon, h 0.401 in. min 0.416 in. max, dia max 0.443 in., across flats 0.367 in. min 0.376 in. max
3b thread class right-hand 20 thread quantity per inch coated with light blue dykem, color no. 15526, fed std 595 over 20 percent or more of surface visible after installation copper threads surface treated