The MXL 4000 is a large diaphragm FET (field effect transistor) condenser microphone. It has three different polar pick up patterns including cardioid, figure 8, and omni. This microphone is designed for use in the recording studio and I wouldn't recommend trying to use it for anything else. The mic usually comes with a shockmount and a custom built windscreen.
I've only used the MXL 4000 two or three times at my friend's home studio, but I feel I've used it enough to get a pretty good read on what this mic can do. I used the mic mostly for recording vocals in Pro Tools and I was pretty happy with the results. I wasn't blow away by the sound quality, but since I was only recording demos the mic worked perfectly and gave me more than enough clarity. While it is rare that you can find a FET condenser microphone that is so cheap, you do get what you pay for as this microphone isn't nearly as good as some of the other more expensive FET microphones out there. As long as you know this going in and don't expect the world from this mic, you will probably be pretty satisfied as it has a pretty good tone for such a cheap microphone. MXL isn't known for making the best sounding microphone out there, but they do offer cheap microphones for home studios for users who want something that sounds good but doesn't cost a whole lot. For the price that the MXL 4000 costs you, I can't really complain too much about the microphone at all, but just don't expect this microphone to do all that great; it will get the job done but definitely isn't a professional quality microphone. All in all, for the price I don't think that you could find a FET microphone that is much better than this one.