Abstract: An apparatus for pack cooling flat stock to be retrofitted to a standard cooling bed. The apparatus includes collecting means having a plurality of stacker arms mounted for movement with respect to the stationary notch bars of the cooling bed between a first, retracted position, in which the arms underlie the notches in the stationary notch bars to permit uninterrupted transport of bar stock across the bed, and a second, lifting position in which the arms can lift a flat bar to a height sufficiently above the uppermost travel of the moving notch bars to permit a successive flat bar being transported across the cooling bed to be received in the notch of the stationary bar just vacated by the flat bar lifted by the stacker arms. Upon the return of the stacker arms to their first position, the flat bar held thereon will be placed on top of the newly-introduced flat bar to form a stack, resulting in a retarded cooling rate for the flat bars in the stack.