Du-Bro 861 - 4-40 Swivel ball link for 4-40 rod (12)Du Bro Swivel Ball Link 4 40 (12) This high quality ball link offers smooth, secure operation with less slop. You'd want to use this on any control surface where accuracy is required (like the throttle linkage). Includes: 12x swivel ball link (Black plastic, self threading for 4 40 rod, 1" in overall length) with a burnished brass ball pre installed with a #4 hole in it 12x 4 40 x 5 8" socket cap screw 12x brass spacer 12x 4 40 steel nut Requires: 4