The DD0297 is a microphone protection grid ideally suited for making all types of far-field recordings.
It is supplied as standard with the Standard Microphone Types 4003 and 4006, the A-B Stereo Kits 3503 and 3506 and the Compact Microphone Types 4051, 4052 and 4053, but can also be ordered separately. With this grid fitted, your microphone will achieve a linear diffuse-field response up to 15 kHz. 
In the near-field, the on-axis response has a 6 dB boost at 15 kHz. At intermediate distances, you can orient your microphone at a "grazing angle" of incidence to the sound source to give a normal response to direct sound while brightening up reflective sound.