In my mind this is the very real advantage in that swingarm. Simple and easy to do and the rear wheel is always in perfect alignment with the front sprocket. I use a Profi-CAT laser alignment tool to do this chore on all my bikes and although it seems to be accurate and do the job well it is still a fiddly thing to get the slack set to my satisfaction and the alignment as it should be. The eccentric adjusters are the perfect answer. Adjust the slack to spec and tighten it down. Done....These Metmachex swingarms are equipped with an eccentric axle adjuster that allows you to make quick easy chain slack adjustments. The axle bolt has a woodruff key installed on the hex head end of the bolt and a flat milled surface on the threaded end of the bolt... This allows the adjuster plates to move simultaneously when making the chain slack adjustment. Simply loosen the axle nut,loosen the four allen bolts on the black eccentric adjuster plates,turn the hex head on the axle bolt to make your chain slack adjustment,tighten and torque the axle nut and four allen bolts and off you go. No more guessing if you've got the rear wheel aligned properly or not.