In a first aspect, the present invention provides an air inlet cover (1) comprising a grille (2) having a plurality of radial elements (3) radiating from a center of said grille (2), each said radial element (3) comprising a vane (4) having a leading edge (5) for positioning further from a fan and a trailing edge (6) for positioning closer to a fan, the leading edge (5) of each said vane being offset from the respective trailing edge (6) thereof by substantially the same angular amount (α) for each said vane (4), whereby the vanes are pitched more steeply closer to the center of said grille (2) than remote from the center of said grille, and a circumferential element (7) comprising a bell-shaped mouth enclosing said vanes (4) and having a plurality of apertures (8) formed in a surface thereof, each respective one of said apertures (8) having a first edge (9) parallel to the pitch of a first respective vane closer to the center of said grille and a second edge (10) parallel to the pitch of a second, adjacent respective vane remote from the center of said grille. In a second aspect, the present invention also provides a power tool comprising a fan and such an air inlet cover (1). The power tool may be a garden leaf blower or a dust extraction machine, including a domestic vacuum cleaner.