The B5D is specifically designed for pressure gradient sensors
The hollow cup circumscribes a volume of air around the capsule in a manner similar to a windscreen. The B5D proves to be very effective with little influence on the sound.

Although not intended for this purpose, this windscreen can also be fitted to the MK4V, 4VXS and 41V microphone capsules or the corresponding Compact Microphones, but the slight treble boost is cancelled out.