base layer bottoms from the merino xtreme collection . the thermowave merino xtreme base layer bottoms are soft and with 220 gsm a base layer for the colder days of the year. the composition of merino wool, polyamide and a polyester lining ensures plenty of warmth and best breathability while you enjoy all the benefits of merino wool. fast moisture-wicking and odour inhibition are the top priorities here. flat seams also provide plenty of comfort, while the wide waistband ensures a good fit.