The Brooks Glycerin GTS 23 is a max cushion stability trainer. The GTS series uses GuideRails to provide guidance-based stability. The latest edition continues Brooks’ move to push all footwear in their lineup from 12mm to 10mm. The Glycerin as a result gets a little more DNA Tuned midsole in the forefoot this year. The shoe features a firm, but cushioned and responsive ride that is best for easy paces but can move a little bit uptempo.