Product review (5 stars): best option
Not technically semi-rigid, but bettereasier to work with and springs back more from crushing.  Springs back less than standard foil tube, but this is due to more durable and fire resistant 5 ply all metal construction with no plastic.  It's really difficult to punch a hole in this, but easy to cut with scissors and a wire cutter to the length you need, plus when it is compressed, you lose almost no airflow capacity.