Shure 545 Unidyne III Dynamic Microphone

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"The Unidyne III microphone cartridge first appeared in the model 545 in 1960. Shure engineer Ernie Seeler was the driving force behind this element, which brought a substantial improvement to the Unidyne platform. A highly-sophisticated pneumatic shock mount was developed which provides best-in-class handling noise reduction. It works by causing the air volume in the rear cavity to exert pressure on the back of the diaphragm when the system is stimulated with mechanical vibration. This "back pressure" prevents the diaphragm and coil from moving in the magnetic gap and the result is no output under vibration conditions." The 545 Unidyne III was the first Shure unidirectional model where the user spoke into the end of the microphone. 
(source: shure.com)

From the Shure 1960 catalog: New! Model 545 "Unidyne III"
The smallest unidirectional dynamic microphone.  Features truly uniform cardioid pickup pattern.    List Price: $85.00    Cable connector: Equivalent to Amphenol MC4M plug   Impedance: Dual. Choice of 50 ohms, 250 ohms, or high.  The Shure Model 545 "Unidyne III" is a new addition to the famed family of Unidyne microphones. This striking-looking, compact, slender , uni-directional, moving-coil microphones features wide-range  reproduction of voice and music and flexibility of uses as hand or stand microphone.  Recommended for dependable use in fine quality P.A. systems, tape recording, fixed-station communications, etc.  Provides highly satisfactory operation under adverse acoustic conditions – reduces or eliminates problems due to feedback and background noise pickup.  Permits placement at a distance from the performer 75% greater than possible with omni-directional microphones.