The SteriPEN® Solar Charging Case, made to store the Adventurer and Traveler, charges 2 CR123 Rechargeable batteries. The Solar Case is designed to clip on your backpack or camera bag. To charge the batteries, just open the case and angle the integrated solar panel toward the sun. The Case will charge two rechargeable CR123 batteries in 2-5 days depending on solar conditions. You can also charge the batteries in a couple of hours using the 110V/240V power adapter (included) or the 12V auto adaptor (sold separately). The Case also provides a storage compartment for a SteriPEN Adventurer or Traveler (sold separately).