Therafin’s versatile Adjustable Height Channel Bracket is attached to a Therafin half tray that is made out of 3/8" clear polycarbonate. Polycarbonate is virtually unbreakable. The fixed (non-flip) bracket slides the tray on from the front. Bracket fits many standard armpads with maximum dimensions of up to 2-1/2″ wide by up to 1-1/2″ tall. Trimline shape half trays have a straight outer edge that offers support for people with weakness on one side and allows more belly clearance.