Abstract: A device for retaining sheets of construction material in a generally upright position includes an elongated base member having an attachment structure at a first end that permits attachment of the elongated base member to a support surface with the elongated base member extending generally horizontally away from a support surface to which the base member is attached. The device further includes a retaining member having a female connecting structure at an upper end of the retaining member. The female connecting structure slidably connects the retaining member to the base member such that the retaining member can be positioned at a selected one of a plurality of positions along the base member. The retaining member further includes a retaining arm that extends downwardly from the female connecting structure. A releasable connecter structure selectively prevents movement of the retaining member relative to the base member in at least a first direction.