The Orbiloc Service Kit contains everything you need to maintain your Orbiloc Safety Light The Orbiloc Safety Lights use two CR-2032 Lithium batteries A pre-wrapped battery pack of two cells comes with all Orbiloc Safety Light models The Orbiloc Safety Light has a very long battery life: 250 hours when flashing and 100 hours when steady-on The tiny O-ring lubricated with silicone is crucial to the Orbiloc Safety Lights remaining waterproof to 100 meters To make sure the Orbiloc Safety Light stays waterproof we recommend the O-ring be replaced every time you replace the battery pack