Bell Sports Corp., based in Scotts Valley, California, sells bicycle lights and other accessories. Its battery-powered tail light fits on the seat post to make the rider visible at night via a flashing red signal. The headlight attaches via a separate bracket to the handlebar to illuminate the road ahead. Check the packaging when you buy the lights; separate batteries are likely required.
Insert a penny in the slot at the bottom of the tail light where the cover and base meet. Lever the cover with the coin so the cover pops off. Capture the rubber seal and replace it if it falls off; it likely will stay in place on the cover.
Place two AAA batteries in the battery compartment so the positive end of each battery (marked by a plus sign) lines up with the "plus" mark in its compartment. The batteries will be facing in different directions.
Press the rubber seal onto the edge of the cover if it became displaced in Step 1. Squeeze the cover back in place until you hear a snap confirming that it seated.
Pinch the silver rim on the sides and rear of the headlight and pull its housing up and back.
Insert four AA batteries in the headlight, again matching the batteries' positive marks with the "plus" marks in the battery compartment.
Line up the housing with the battery cover and push it straight down in place until you hear a click.
Test the lights by pressing their power buttons once. If they don't start blinking, repeat the battery insertion step, double-checking that the polarity is correct. Test the battery quality with a multimeter to confirm that it falls in the "good" range.
Don't combine old and new batteries in the same bicycle light.