These arm rest supports can be used as replacement items, or in new do-it-yourself open-back style seat construction.
Note that in this "family" the "curved" term is rather obscurely derived from the shape of the vertical section of the arm rest.
See Related Products, below, for the matching back support - which, in spite of being named 'curved' is actually quite straight.
• Anodized aluminum extrusion is 0.5" thick and 2" wide
• Pre-formed and drilled
• Sold by the pair
As an example, this hardware is used in Garelick's #940 Ladder Back Flip-Up Bolster Seat.