The X8 uses SF and SFP propellers. Labels are found on the individual propeller packages and on the propellers themselves. The diagram below shows which motors require SF or SFP propellers. Accurate assembly of SF and SFP propellers is critical for the X8 to fly correctly.
To attach each propeller, remove the nut and washer from the motor, and add the correct type of propeller with the writing on the propeller facing the sky. (This is a tight fit; apply pressure and twist the propeller onto the motor.) Replace the washer over the propeller, and use the propeller wrench to tighten the nut on top.