I know it's not the best one out there but hey its boost. so I don't want to here how they break I know already and fixed one of my friends. but, to the question what is the differance from a BD-11 vs. BD-11A ? every where I check they never compair them they either list one or the other and one artical said the BD-11 was there better replacement for the BD-10 and BD-600 but, jumped strait to the new gear drive powerdyne.