Cold Activated 26mm crown bottle caps. These caps will turn blue and display a "Ready To Drink" message when they reach a cold enough tempearture (41°F)! These caps also have an oxygen absorbing liner that will absorb any oxygen left in the headspace. This helps reduce the oxidation that happens during the bottling process, keeps your home brewed beer tasting fresher, and can extend it's shelf life.
Important to note: It is recommended that you only sanitize as many caps as you'll require at the time of bottling. The oxygen-absorbing agent is activated when the cap gets wet. If wetted caps are saved for later use, they'll still function as a normal cap, but the oxygen absorbing agent may be depleted.