Abstract: A filter device is adapted to separate impurities from a fluid. The filter device has a hollow filter body being elongated and having an end that is formed with an inlet, an opposite end that is formed with an outlet, and an inner surface that extends helically from the inlet to the outlet. The filter device further has a helical channel defined by the inner surface and communicating spatially with the inlet and the outlet. When the fluid flows along the helical channel from the inlet to the outlet, the impurities are drawn to be attached to the inner surface and the filter body by a centrifugal force, thereby being separated from the fluid.

Abstract: A hard seat device is adapted to be mounted on a seatpost of a bicycle for supporting a hard protective cycling pad thereon, and includes a hard seat member and a linking unit. The hard seat member has a main body that is adapted for contacting the hard protective cycling pad, and that is elongated without any part expanding laterally for supporting buttocks of a rider. The linking unit is mounted to the hard seat member and is adapted to be coupled to the seatpost.

Abstract: An aerator for injecting air into water includes a hollow tube having an inlet end and an outlet end, a hollow dish-shaped element including an upper conical portion and a lower conical portion, blades and a rotating element. The upper conical portion is connected the outlet end. The lower conical portion is located under the upper conical portion. The lower conical portion is spaced from the upper conical portion by a first distance. Each of the blades is connected to the upper conical portion and the lower conical portion, and the blades are arranged in a spiral shape. The rotating element rotates the hollow tube, the hollow dish-shaped element and the blades. The blades strike the water to suck the air through an air intake hole of the inlet end into the hollow dish-shaped element, thereby injecting the air into the water under negative pressure.

Abstract: A hard protective pad for pants includes a support plate made of a rigid material. The support plate includes two spaced-apart concave portions extending inwardly from a top surface of the support plate and configured to match the shape of the buttocks of a user, and a fixing portion between the concave portions. The fixing portion extends arcuately inwardly from a bottom surface of the support plate and configured to match the shape of a bicycle seat.

Abstract: A handheld propulsion assembly includes at least one propulsion subassembly. In the propulsion subassembly, pivot and hinge mounts are disposed respectively on upper and lower surfaces of a floatable board member, a crank shaft is pivotably mounted on the pivot mount about a pivot axis, a crank arm extends radially from the crank shaft, and a blade is hinged to the hinge mount. When a driven portion of the crank arm is driven to swing back and forth, the floatable board member is correspondingly moved forward and backward. The blade is angularly movable about a hinge axis between an unfolded position, where the blade has a maximized propelling force, and a folded position, where the blade has a minimized propelling force.

Abstract: An ergonomic water paddle for a watercraft includes left-hand and right-hand arms, a cross piece, and left and right paddle bodies. The left-hand arm extends lengthwise to terminate at left front and rear ends. The right-hand arm extends lengthwise to terminate at right front and rear ends. The left paddle body is connected to the left rear end. The right paddle body is connected to the right rear end. The cross piece is disposed to connect the left front end to the right front end to permit the left and right paddle bodies to be moved synchronously with each other in each paddling stroke.

Abstract: An air blade is provided. The air blade includes a body, an airflow channel and an anti-resistance structure. The body has a central axis. The airflow channel is located on one side of the body, and is parallel to the central axis of the body. The anti-resistance structure is located on the other side of the body, and corresponds to the airflow channel.