When buying a kids' bike helmet, there are a few things you need to keep in mind. Size is obviously important, as you want the helmet to fit your child properly. You'll also want to make sure the helmet is certified by a safety organization like the CPSC or Snell.One other thing to look for when purchasing a bike helmet for your child is adjustability. Many kids' helmets have adjustable straps and headbands so that they can grow with the child. This is important, as a properly fitted helmet is key to preventing injuries in the event of a crash.Finally, be sure to read up on proper installation and wearing tips before your child takes their new bike helmet out for its first spin!