Montbell Base Layer Kids' Unisex ZEO-LINE Middle Weight Round Neck Long Sleeve Crew 1107273The latest evolution of Montbell base layer spinning technique utilizes high quality micro fibers to produce coiled or "crimped" threads. Compared to traditional fibers, the refined microfibers present in Zeo Line feature greater surface area and smaller air pockets to better trap air, yielding superior heat retention. Featuring a three layer knit structure, Zeo Line maintains an air layer between dual fabrics. The layer closest to your skin pulls