A surgical stapler, comprising: a support base; a trigger located at a proximal end of the support base; a handle located at a proximal end of the support base; a retaining pin operatively connected to and extending distally from the support base, the support base being operable in the surgical stapler to cause the stapler to position staples near tissue; at least one blocking plate (102, 103) in the stapler; and a unit lockout rotatable about a pivot fixed to the handle, the unit lockout comprising: an upper end; and another end facing the trigger to prevent it from firing when the upper end is blocked from moving freely by the at least one blocking plate, wherein the upper end of the unit lockout is movable relative to the at least one blocking plate so that the upper end of the unit lockout is no longer blocked from moving freely by the at least one blocking plate to permit the unit lockout to rotate about the pivot, wherein the at least one blocking plate comprises: a connect cover plate to which the retaining pin is rigidly connected and extended distally therefrom, wherein when the retaining pin is not moved distally the connect cover plate blocks the upper end of the unit lockout from moving freely; and characterized in that said at least one unit lockout further comprises at least one lockout plate rigidly connected to the support base and movable relative to the handle, the upper end of the unit lockout being movable relative to the lockout plate, wherein when the upper end of the unit lockout has not been moved distally the lockout plate blocks the upper end of the unit lockout from moving freely. a support base; a trigger located at a proximal end of the support base; a handle located at a proximal end of the support base; a retaining pin operatively connected to and extending distally from the support base, the support base being operable in the surgical stapler to cause the stapler to position staples near tissue; at least one blocking plate (102, 103) in the stapler; and a unit lockout rotatable about a pivot fixed to the handle, the unit lockout comprising: an upper end; and another end facing the trigger to prevent it from firing when the upper end is blocked from moving freely by the at least one blocking plate, an upper end; and another end facing the trigger to prevent it from firing when the upper end is blocked from moving freely by the at least one blocking plate, wherein the upper end of the unit lockout is movable relative to the at least one blocking plate so that the upper end of the unit lockout is no longer blocked from moving freely by the at least one blocking plate to permit the unit lockout to rotate about the pivot, wherein the at least one blocking plate comprises: a connect cover plate to which the retaining pin is rigidly connected and extended distally therefrom, wherein when the retaining pin is not moved distally the connect cover plate blocks the upper end of the unit lockout from moving freely; and characterized in that said at least one unit lockout further comprises at least one lockout plate rigidly connected to the support base and movable relative to the handle, the upper end of the unit lockout being movable relative to the lockout plate, wherein when the upper end of the unit lockout has not been moved distally the lockout plate blocks the upper end of the unit lockout from moving freely. a connect cover plate to which the retaining pin is rigidly connected and extended distally therefrom, wherein when the retaining pin is not moved distally the connect cover plate blocks the upper end of the unit lockout from moving freely; and characterized in that said at least one unit lockout further comprises at least one lockout plate rigidly connected to the support base and movable relative to the handle, the upper end of the unit lockout being movable relative to the lockout plate, wherein when the upper end of the unit lockout has not been moved distally the lockout plate blocks the upper end of the unit lockout from moving freely.