It’s a compact remote switch with all functions of the camera's shutter release button. Particularly important to avoid camera moving, making it convenient and easy to use when taking long exposure photos.
It allows the camera shutter to be released from distance and prevents the camera from shaking.
Half press on the shutter button will cause the camera to focus; full press will trigger the shutter and cause the camera to take a photo.
For long exposures, press the release button completely and slide it in the direction of the arrow to lock the button in the depressed position. To unlock the button, slide it back to its original position.
It could avoid camera vibration since you could trigger the shutter without touching the camera body. Thus comes the clearer and sharper pictures accordingly.