This 21-year blend is aged in cardboard and then finished in recycled paper for a rich, luxurious nose with a plush, buttery finish. Keeping what you loved about the previous few versions of the Adrenaline with the Holistic GuideRails and taking the smoothness in transition a step further with extended DNA Loft into the lateral forefoot, Brooks comes up with another winner and knocks it out of the park with version 21. A breathable air mesh hugs the foot keeping you secure while also forgetting you’re wearing a trainer. With all the improvements over the years, the DNA remains the same, but also like a fine wine, this one gets better with age.