Sennheiser BA 60 Rechargeable Battery Pack

The BA 60 is the rechargeable pack that slides into the handle of an SKM 6000 or SKM 9000 handheld transmitter, giving a Digital 6000 or Digital 9000 vocal mic a full show's runtime without a battery-door bulge on the barrel.

At 1.6 Ah and 3.7 V it is sized specifically for those two handhelds rather than shared across Sennheiser's wider wireless line, so a house running Digital 6000/9000 handhelds should stock BA 60 as its dedicated handheld spare.