The Manfrotto Alu-Core allows you to use the Expan system with uncored paper or cloth backgrounds. It consists of two aluminum sections which interlock by means of a joining casting. The Expans (available separately) are inserted into the Alu-Core and provide a core for background rolls. This Alu-Core is 9' (2.7 m) long, when assembled. It replaces old catalog #2922.