Abstract: Sheet extrusion of elastomeric material wherein an extruded strand is passed through a die having a symmetrical runner system which divides and subdivides said strand into multiple strands equal in length and cross section, and then gradually transforms the multiple strands into laterally adjoining flattened triangular portions in which substantially the same cross-sectional area is maintained as the cross-sectional shape changes, with alternate triangular portions overlapping the other triangular portions in staggered relation and all of said triangular portions terminating in a continuous lateral exit slot.