A support arm for supporting an item from a tapered member such as a tapered chair arm includes an arm portion having a proximal end and a distal end. At or toward the distal end is an arrangement for mounting an item. At or toward the proximal end is an attachment portion defining an internal taper. The support arm is engageable on the tapered member in a taper lock between the tapered member and the attachment portion and disengageable manually and without the use of tools, to mount the support arm to the tapered member. The item is preferably a tablet. One or more release shuttles may be provided within the attachment portion to enhance the disengagement of the support arm from the tapered member.