The Glycerin GTS 23 delivers the plush, premium cushioning of the Glycerin series with the added confidence of Brooks' GuideRails support system. DNA TUNED cushioning provides a soft, smooth ride mile after mile, while GuideRails work holistically to keep your body moving in its natural motion path — reducing excess movement without restricting your stride. For runners who want max comfort and a little extra support, the Glycerin GTS 23 is the complete package.