The MA-505 series is a dynamically balanced tonearm. It reacts completely differently than a statically balanced arm for tracking purposes. The mass is 14.5g (with the standard Micro Seiki headshell) and it was designed primarily to work with all cartridges, but especially with very high compliance cartridges which were all the rage when this tonearm was designed. But it works great with moderately low compliance or heavy cartridges. It's one of my favorite "budget" tonearms.
