The 523 is a 3XL version of the 516. To compensate for the additional leverage generated from the extended length I increased the wire diameter by one size, e.g. 523 #10 and 516 #8 have the same wire diameter.
This is a 3X long hook with a 1X gape. It has a down eye and is formed from a heavy weight wire. It is be available in sizes #4 to #14.
As with all Firehole Sticks, this hook is made from high strength carbon steel, which is properly hardened and tempered. The hook is chemically sharpened and finished with a black nickel coating.