The Beta line takes the Shure SM family of live mics and upgrades them: neodymium magnets for hotter output, tighter polar patterns for better feedback rejection, brighter top-end for cutting through a mix.
The Beta series is Shure’s line of upgraded dynamic mics for live work. Compared to the SM line, the Beta mics use neodymium magnets (hotter output, less preamp gain needed), supercardioid polar patterns (tighter pickup, better feedback rejection), and brighter top-end tuning.