Why have different PZM microphone models?

Crown makes different PZM models for different or specialized applications.

The PZM-30D and PZM-6D are identical in response and share the same capsule and circuit design, and require phantom power. However they have different chassis designs and features.

The PZM-30D is larger, with the XLR connector built into the plate. It accepts a detachable mic cable. Use it when you need extra ruggedness, either in the studio or on the road.

The PZM-6D is smaller and lighter, with a permanently attached thin cable and XLR connector at the end. Use it when you need a light, inconspicuous microphone. For example, tape it to the underside of a raised piano lid, or tape it to a clear plexiglass panel.

The PZM-10/10LL and PZM-11/11LL/11WR are  designed for security, surveillance, and observation room applications. They can be mounted on the ceiling or wall other locations where they won't be easily noticed. The PZM-11LLWR has the added ability to be mounted outside in the elements due to its weather-resistant housing. The Sound Grabber II is a low-cost, high impedance, unbalanced microphone designed for general-purpose consumer use such as office meetings, group discussions, interviews, home video productions, and music recordings. An internal 1.5V AAA battery powers it. The PZM-185, while sharing the same appearance as the Sound Grabber II, is designed as a balanced, low impedance device. It is powered by an internal AAA battery or phantom power.