2a thread class right-hand 1.550" thread length flat chamfer head style 8 thread quantity per inch the bolt is a castellated hex head, 8 slots equally spaced at 0.286" apart un thread series
2a thread class right-hand flat chamfer head style 11 thread quantity per inch the item is a socket set screw, and the head dimensions are 0.3125 in. minus unc thread series
2a thread class right-hand 0.250" thread length flat chamfer head style 32 thread quantity per inch point on threaded end 0.114 in. min to 0.130 in. max dia., 0.156 in length. fastener head straight knurl passivate surface treated unf thread series
3a thread class right-hand 1.891" thread length double hexagon extended washer head style 13 thread quantity per inch cadmium surface treated unc thread series