The Shure SM58 Microphone is a sturdy, well-made, and might I add excellent, dynamic microphone.  I've used the SM58 for years as both a vocal microphone as well as an instrumental mic (in instances where it's preferred over a condenser).  The sm58 has held up wonderfully and given the quality of sound that I desired.

The Shure SM58 microphone is a unidirectional (cardioid) dynamic vocal microphone.  It's great as both a singing microphone as well as a speaking microphone.  It uses a built-in spherical filter that minimizes wind and breath "pop" noise. A cardioid pickup pattern isolates the main sound source while minimizing unwanted background noise.

The steel mesh head construction means it will survive the occasional drop - which does happen and I've experienced it.

The SM58 accentuates the warmth and clarity (brightened midrange and bass rolloff) of lead and back-up vocals which has made it the first choice of performers everywhere. 

Internally, it has a pneumatic shock-mount system which cuts down on handling noise.

Stats:

Frequency response is 50 to 15,000 Hz.

Sensitivity (at 1,000 Hz Open Circuit Voltage)

-54.5 dBV/Pa (1.85 mV)

1 Pa = 94 dB SPL     

Impedance

    Rated impedance is 150 ohms (300 ohms actual) for connection to microphone inputs rated low impedance

Polarity

    Positive pressure on diaphragm produces positive voltage on pin 2 with respect to pin 3

Net Weight

    298 grams (10.5 oz)

The is a workhorse of a microphone that performs great time after time.  Used by professionals for years, it's proven itself an amazing microphone.