A mini-fan (126) is implemented for installation in a recess (124) of a wall (122), which wall is equipped on the periphery of the recess (124) with a plurality of retaining members (128, 129). The fan has, for air guidance, a housing (136) that, in its installed position, projects with a housing portion (127) approximately complementary to the recess (124) of the wall (122) into that recess. Arranged on the periphery of that housing portion is at least one part (138) made of an elastomeric material, with which part the fan (126) is introducible, upon its installation with the part (138) made of elastomeric material with displacement along the wall (122), into the retaining members (128, 129), in order to bring that part (138), in the installed position, at least locally into sealing contact against the wall (122).