Fletcher designed his ''Breuer'' (aka Sumiko MDC 800) as an
''universal tonearm''. In contradistinction to Breuer who refused
to provide his customers with any other counter weight than
the original Fletcher designed 6 counterweights for the MDC 800.
Those are meant for carts from 6 - 20 g . The idea being to get
the counterweight as near as possible to the pivot for each cart.
I never owned a Breuer but well EPA 100 and EPA 100,mk2.
Technics designed an complex counterweight but its weight is
not sufficient for carts of, say, 9 g and above. To put this as
simple as possible EPA 100 is suitable for the MM carts but
not for the MC carts.