Unscrew the back battery housing panel and insert the three AAA batteries into the housing. Screw the panel back on and undo the ratchet strap completely.
Place the Opticube onto the center of the handlebars - to the left or right of the stem. Bring the strap under the bars and marry the two strap ends together so the end sticks out of the black ratchet locking device. Pull and down on the ratchet to tighten the strap thus securing the light to the handlebars.
Press the rear Drop-Out button to pop the front of the light free. Pull up and out to remove the light from the mount, or back and down to snap it back onto the mount.
Push the switch on the back of the Opticube to the first setting for the bright light, the middle for the midlevel light and third position for the blinker. Push it all the way to the left to turn it off.