The DPA 4021 is a phantom powered (P48) condenser microphone using the same type of cartridge as the famous DPA 4011, but is preamplified using a built-in ultra-small thick-film mounted FET-preamplifier. The result is the world's smallest studio quality cardioid condenser microphone, that runs directly on phantom power with no external preamplifier needed.

The 4021 has its cable (3 m as standard) side-mounted, which mechanically is perfect for situations where the microphone needs to be mounted directly on the musical instrument or on a stand. The linear frequency response from 40 Hz to 20 kHz (±2 dB) together with the ultra-small design makes Type 4021 the perfect choice whenever high definition audio and insignificant size is paramount.