M 221 series
At first only the M 934 switchable omni/cardioid capsule was offered. Then at the request of German broadcasters three further capsules were introduced, including two types of the CM 9 omni shown in the picture, and a single-pattern cardioid (type CR 3/1).
Late in 1955 the M 221 A was introduced with an improved circuit for even lower distortion, along with an alternate version for German broadcasting known as the M 155.