From the manufacturer:
This is a precision tooled (+) screwdriver bit for use with the Ratcheting Screwdriver PRO. At 55mm long, it is the perfect length for working on your R/C car's screws. Can be used on (+) screws between 3mm and 5mm. Crafted in chrome molybdenum vanadium steel. Bit size is laser-engraved on the end of the shank for easy identification.