World War II ww2 us army 10th mountain division ski riding boots size 8.5 type 4. No dates, but these were made until 1943.
Left start - excellent condition. Size 8.5 c (regular). Right boot - missing side brass parts. Size 8.5 e (large). They both measure the same thing at 12.5 heel on foot (sole) and 4.75 at the widest point through the middle of the feet.
No notable difference in size, except perhaps a 1/8th inch width inside which is not noticeable wear. These are of us size 8.5 but adapt a little more as they are intended to be worn with thick felt soles and thick wool socks. So, about a size 9 for a regular shoe carrier. Type 4 mountain ski boots were the first to have rubber soles. Here's an article of mountaintroops.
Known as spec 31b boots, they were an improvement, but the need for two versions was not practical. Work began in November 1942 on the adaptation of the Braman rubber soles to the bqd 31b boot and, in June 1943, contracts for mountain and ski shoes with rubber soles were awarded to three companies. The attachment of the single-piece moulded rubber sole to the ski shoe created a technological challenge that took up until mid-summer 1943 to overcome, but the sole proved to be one of the major innovations of the quartermaster body during the Second World War.The rubber sole gave a better traction overall, was quieter on the rocks and worked well for walking and skiing.