This piece was missing right out of the box. If you're looking at Masterpiece Skywarp in vehicle mode so that the nose cone is pointing at you and the thrusters are away from you, it's the left most (outboard) flap. Although geometrically both left and right flaps are identical, there are sprue/mold lines on one side of each flap that differentiate each one. I'd be willing to pay for a spare beat up or incomplete MP Skywarp or even an MP Starscream that I could repaint. Thanks!