UGG. 1017275 SLA. OLIVERT. SLATE.Meet our most essential winter boot built to get you through even the harshest weather. Rated to withstand temps as low as -20 C the Olivert is rugged and tough with edgy hiker styling. Crafted with waterproof leather it s packed with cold weather-ready features like soft wool lining a layer of fleece another layer of Thinsulate insulation and a sole that stays flexible no matter what even in freezing ice and snow.