The release button reacts fast and fine. # Lock the button for long exposures or continuous shooting. # Two-stage release button: Halfway pressing for auto-focus, complete pressing for taking pictures. * Press it halfway to activate the auto-focus. * Press it completely to shoot. # Slide to lock. Press and slide it to lock the shutter for Bulb Mode photography. # Avoid Camera Vibration = Sharper pictures! # Since you can trigger the shutter without touching the camera body, it can avoid camera vibration, thus resulting in sharper pictures. # Compatible with:Olympus PEN E-P1 E-P2 E-30 E-620 E-550 E-520 E-510 E-450 SP510UZ 550UZ 560UZ 570UZ 590U Package includes: One transmitter, one receiver, one CR-2 battery.