D4*40*D2*20*0# Ø4 wing-type round shank screwdriver bit, length 40mm, stepped down to Ø2 length 20, 4-point tip size #0

D4*40*D2*20*0# 4mm wing-type  screwdriver bit, 40mm length, stepped down to 2mm diameter x 20 length, Phillips #0 tip

Used for torque-controlled screwdrivers.

S2 steel material