An O-ring and a side channel blower employing an O-ring for providing a gap-free, air-tight seal of the blower channel and side-by-side pressure and vacuum ports. The O-ring includes a generally circular, main O-ring have two free ends for sealing a majority of the blower impeller channel, and two relatively smaller O-rings, each of which is attached to an opposite one of the free ends of the main O-ring and are spaced apart in a side-by-side manner and are connected to one another by a bridge member. The small O-rings are configured and dimensioned so that one of the small O-rings serves to seal the vacuum port of the blower and that the other of the small O-rings serves to seal the pressure port of the blower, with the two small O-rings and bridge member and free ends of the main O-ring arranged to create a generally spectacle-like shape.