A product flow control apparatus for use in a gravity slide sorter for sorting products; each of said products having thickness; said gravity slide sorter having a product viewer, said product viewer defining a scan line; said gravity slide sorter sorting products based on comparison of pre-determined criteria to output from said product viewer; said gravity slide sorter having at least one inclined slide; said inclined slide having a slide upper end; said inclined slide having width; said product viewer positioned adjacent said at least one inclined slide; said inclined slide having an operating cross sectional area, said operating cross sectional area being the product of said inclined slide width and said product thickness; said inclined slide having a length and incline sufficient to obtain singulation of said products before said products reach said scan line; comprising: a product reservoir; said product reservoir containing said products to be sorted; a flow-rate control passage; said flow-rate control passage having an upper orifice, a lower orifice, a first side, and a cross-sectional area; said flow-rate control passage upper orifice being in communication with said product reservoir; said flow-rate control passage lower orifice being in communication with said at least one inclined slide; said flow-rate control passage being vertically disposed; a flow valve; said flow valve intermediate said product reservoir and said flow-rate control passage; said flow valve operable among a first flow-valve position and a second flow-valve position; said flow valve terminating communication between said product reservoir and said flow-rate control passage in said first flow-valve position; said flow valve permitting communication between said product reservoir and said flow-rate control passage in said second flow-valve position; said flow valve near-instantaneously repositioned between said first flow-valve position and said second flow-valve position; a flow restrictor; said flow restrictor operable among at least one flow-restrictor position, said at least one flow-restrictor position including a first flow-rate-control position; said flow-restrictor reducing said cross-sectional area of said flow-rate control passage at said first flow-rate-control position; said cross-sectional area of said flow-rate control passage at said first flow-rate-control position comparable to said operating cross sectional area of said inclined slide; said flow restrictor presenting a downwardly-inclined face to said products at all times. a product reservoir; said product reservoir containing said products to be sorted; a flow-rate control passage; said flow-rate control passage having an upper orifice, a lower orifice, a first side, and a cross-sectional area; said flow-rate control passage upper orifice being in communication with said product reservoir; said flow-rate control passage lower orifice being in communication with said at least one inclined slide; said flow-rate control passage being vertically disposed; a flow valve; said flow valve intermediate said product reservoir and said flow-rate control passage; said flow valve operable among a first flow-valve position and a second flow-valve position; said flow valve terminating communication between said product reservoir and said flow-rate control passage in said first flow-valve position; said flow valve permitting communication between said product reservoir and said flow-rate control passage in said second flow-valve position; said flow valve near-instantaneously repositioned between said first flow-valve position and said second flow-valve position; a flow restrictor; said flow restrictor operable among at least one flow-restrictor position, said at least one flow-restrictor position including a first flow-rate-control position; said flow-restrictor reducing said cross-sectional area of said flow-rate control passage at said first flow-rate-control position;