A flat display screen including a. An orientation of an axis of easy magnetization of the magnetic grains is three-dimensionally distributed. At least two paddle-shaped markers extend away from a respective one of the strut ends. The dust collection part captures toner that has passed through the duct together with an airflow generated by the first fan. Differential or laterally asymmetric design of the reverse gate compensates for vorticity or swirl in the waterjet to help ensure uniform watercraft performance when travelling in a reverse direction and turning either to the right or to the left.