We designed these beautiful cable drums when we realized that most of the offerings used threaded center holes and tended to loosen causing the drum to spin freely on the throttle shaft, that didn't work out too well so we designed ours with a "D" shaped hole to match the throttle shafts exactly preventing any possibility of ever coming loose. But we always try to make things better than everyone else so we added additional cable locations so instead of the common 8 position drums the PJS drums have 12 positions to accommodate just about any application ! Billet 6061 T6 aircraft aluminum (of course!) and precision CNC machined to exact tolerances, these are the best and most widely used on the market. Sold by most major distributors it's no wonder these are the number ONE drum on the market !