in the kit there is both an M3 x 0.5 and an M3 x 0.6
That's proper weird. M3.5×0.6 would be useful around the house as it's the face plate mounting screw size for electrical fittings. M3.0×0.6 seems to be a mounting thread for ultrasonic dental tools 🤷🏻♂️
Well, colour me confused, in the kit there is both an M3 x 0.5 and an M3 x 0.6