The AV Stumpfl SK21 is a roll-up transport box for Magnum projection screen systems with fabric widths up to 500 cm. It is identified by manufacturer article number BRV-SK21/500 and belongs to the Magnum product series. The internal dimensions are specified as 260 × 330 × 550, although the source does not state the measurement unit or dimension order. The listed net weight is 81 kg.