Choose your screw direction. Normal (clockwise, silver) will work for most airplane motors. Reverse direction (counter-clockwise, black) is offered for reverse multicopter motors.
Sold as pairs of two, same direction.
These nylon-steel nuts will firmly grip a prop shaft without the need for loctite. 5mm inner-diameter in size, they will fit the standard shafts of many multirotor and airplane motors, particularly 22mm stator motors (22xx). The ribbed flange of these nuts will also keep a firm grip on the propeller.