While Walker GHS (Grass Handling System) mowers use an internal blower and center discharge for collection, each GHS model can also be ordered in a Side Discharge (SD) configuration, which is popular for non-collection applications, including mulching. Machines with side-discharge configuration are compatible with a variety of side discharge and mulching decks and can also power Walker attachments. Key Specs: MT23 & MT26 EFI MTL31 EFI MC & MD MS