A slider opens or closes a rigid elongate reclosable fastener (40) lying in an X-Y plane and sealable in a Z direction orthogonal thereto. The slider (100) is slidably attachable to the fastener (40) and imparts forces to the fastener (40) in the Z direction to open or close the same as the slider (100) moves along a travel path having vector components in the X and Y directions. The slider (100) biases interlocking elements of the fastener into engagement with one another as the slider (100) moves in a first direction and separates the interlocking elements as the slider (100) moves in a second direction.