The overall length of the jig is only 30". This jig has some of the "bells-n-whistle's" on it as discussed in the Crafting the "Compact Flemish Jig" article which include the 0", 3" and 8" ruler lines scribed along the front-end, the table of Strands-to-Bow Weight noted on it for handy reference, and the cutting-groove between the two rows of nails on the right end of the jig. Also note the direction arrows on the jig which indicate the path the B50 Thread is wrapped.
The large nail in shown just left of center in the photo is the "peg". The peg is placed in the appropriate hole (currently it's positioned in the 62" hole) depending on the length of the bow the string is being made for. See the Using the "Compact Flemish Jig" article for details in these regards.