I have had a Black and Decker, 20v, cordless trimmer. Single line, auto feed. I don’t care if I have to let go of some features I just want and easy string replacement other than the prestrung spools. I’d like more than a single string, be able to use heavier gauge. I just don’t know what kind of universal head replacements will fit. I don’t care about auto feed or edger functions. It’s not great as an edger. I can use a dedicated edger. If any of these changes are doable point the way. I can remove the auto feed trigger in the spool housing.