PURPOSE: To position and fix an outer cylinder and an inner cylinder freely and intermittently via an engaging member by sliding both cylinders so as to freely adjust width of a hub body by constituting the hub body which constitutes a reel and in which a pair of flanges are fixed at both ends out of the outer cylinder and the inner cylinder which is engaged with the outer cylinder.

CONSTITUTION: A reel R1 which is used for winding magnetic tape, TAB tape, etc., consists of flanges 11, 13 which are fixed at both ends of a hub body 10, and the hub body 10 consists of an inner cylinder 15 and an outer cylinder 17. The tip of inner cylinder 15 is inserted into the outer cylinder 17. Ball 24 which is imbedded on the outer peripheral face of inner cylinder 15 and energized by a spring 23 is positioned and pushed as it is in a guide groove 29 which is formed on the inner peripheral face of outer cylinder 17 to position and fix both cylinders 15, 17 by engaging the ball 24 with hole 25. Also, the inner cylinder 15 is inserted further, and positioned and fixed at a second position by engaging the balls 24, 24 with the holes 25, 27, respectively. That is, both cylinders 15, 17 are allowed to adjust width of the hub body 10 only by the space of holes 25, 27.