These tubes have a 2¾" inside diameter and unique design that permits telescoping from fully closed 18½" length to a fully open 43" length. Twist-lock feature at desired lengths. Made of durable black plastic, tube is water-resistant and ideal for drawings, maps, posters, and more. “Twist-off” screw cap has window for viewing contents inside tube and identification label to mark its contents. Adjustable length shoulder strap allows tube to extend and provides convenient portability.  Assorted cap colors.