Bottom door sweep

Hi: We have a steel exterior door, and the door sweep is gone. The original sweep was a composite U shape, with plastic on the inside, and aluminum, or steel to the outside, thus creating a thermal barrier (I guess) and rubber sweeps to the bottom. We have tried plastic U shaped, but they just do not do well in the winter. Do you carry anything like this, or are they no longer manufactured? The sweep's two parts are snap clicked together. Thanks