The Brooks Glycerin GTS 21 is a robust and well-constructed daily trainer, ideal for those requiring moderate stability. It's extremely cushioned, comfortable, and supportive, with an outsole that lasts forever. However, we also noticed that the upper tends to run warm and the shoe doesn’t perform well at faster speeds, limiting its versatility across different weather conditions or paces. Despite these issues, we think it's still an exceptional pick for those seeking some support without committing to a full stability model. * Reasonable weight gain over non-GTS version * Super comfortable upper * Fantastic non-intrusive stability * Responsive supercritical foam * Built-like-a-tank outsole * Roomy toebox