Commercial-type lawn mowers, whether they are walk-behind or riding mowers, normally Commercial-type lawn mowers, whether they are walk-behind or riding mowers, normally Side discharge mower decks, however, can be problematic when the grass clippings are not sufficiently discharged or directed to the side discharge opening of the mower deck. This can lead to clumping or aggregation of grass clippings on the ground and/or buildup of grass clippings on the underside of the mower deck. Accordingly, there is still a need for a side discharge mower deck that can sufficiently direct and discharge grass clippings.