Tightly woven wool shell sock. The ultimate heat amplifier inside climbing and ski boots. The thick wool has extreme thermal insulation properties. Used by polar adventurers and professional users.
Place a paper close to the wall and with bare feet place the foot on the paper, with your heel to the wall. Since it is important to stand up straight, preferably have someone help you draw a line in front of the longest toe. Remember to measure both feet as they might not be identical. With a ruler, confirm the measurement in centimeters and add additional space according to the list below.
Hunting and Hiking
Note that this method is purely intended as a guideline.