This M6 Propeller Prop Nut Cap CW CCW for 2212 920KV Brushless DC Motor is the set of two different i.e CW and CCW Nut Cap for 2212 and 920KV brushless motor to be fitted above the propeller.
Prop nuts of different directions usually come in different colors, such as black and silver for better user-friendliness.
Some mini quad motors are labeled CW and CCW, and it can cause a hell of confusion for a lot of people in this hobby including experienced quadcopter builders.
Basically, CW (clockwise) and CCW (counterclockwise) motors are still the same motors, apart from the prop shaft threads which have opposite direction. That means for a CCW motor, the prop nut is secured by turning clockwise. And for CW motors, the prop nuts need to be rotated anti-clockwise in order to fasten.