SOREL Boots. This version of the Caribou has the same waterproof construction, full-grain leather upper and iconic silhouette you know and love, but comes with a wool inner boot (instead of felt) to keep feet warm, dry and cosy during activities in winter weather. Removable 9 mm felted wool inner boot, knit wool snow cuff, 2.5 mm bonded felt frost plug, shell in handcrafted waterproof vulcanized rubber and SorelTM AeroTracTM non-loading outsole complete these extraordinary men's boots. Soft Leather, Rubber