Silver BCY 3D Archery Bow String Serving Spool. BCY 3D bow string serving is a great all around material. With a diameter of .017 it is constructed of 3 ply twisted Dyneema or spectra material. It allows for servings to be tight but flexible. BCY 3D serving is a great choice for end serving on a bowstring or cable and also serves well to tie in drop away rests, peep sights and nocking points. The breaking strength is 65lbs and a jig spools contains 120 yards.