All OrcaTorch dive lights come with 3 O-rings already installed on the dive lights. We also send 3 spare O-rings in each new light package when it comes time for a replacement. Here’s how to install O-rings on OrcaTorch dive lights:1. Open the dive lights and remove the O-rings;2. Put silicon grease in a bag;3. Put the O-rings into the bag and rub them well;4. Install the O-rings on the dive lights.Do not use your OrcaTorch dive lights without 3 properly fitted and lubricated O-rings. This can result in flooding and a complete failure of your light. Clean and lubricate O-rings will keep them soft and flexible which is very important to their ability to seal your light from water intrusion.