A directional “shotgun” mic that fastens to the hotshoe of any DSLR type camera.  It comes with a battery that can be recharged over a USB connection, or you can use regular AA’s if you need to.   It has a 3.5mm jack for plugging into the camera.  You can control low frequency roll-off and it’s output level.  It has a foam covering to minimize wind noise, and its rubber suspension isolates handling noise.  How is different from the VideoMic Pro?  It does its processing using digital switching for a cleaner sound, and it’s a bit bigger.