Low on energy? We gotchu. Rambler Sparkling Energy is an all-natural Sparkling Texas Yaupon Tea, sourced from CatSpring Yaupon in South Texas. Featuring 75mg of plant-based caffeine, 5 calories per 16 oz. can and zero sugar. Rambler was inspired by the crystal-clear limestone-filtered swimming holes that defined our childhoods. We’re committed to conserving these natural areas in our backyard and yours for future generations, which is why we partner with like-minded programs across the country at the local level.