Summary: The Shure 577B is a close talking low impedance dynamic microphone with a very effective noise canceling system. The case feels solid as a rock and the PTT switch has a positive feel. Shure claims it to be a "Million-Cycle" switch. The coiled cord seems to be very high quality and durable as well. This mic isn't for everyone, but some will appreciate it's unique features. In my case I wanted to go mobile in my convertible.