Having previously mainly worn Merrell or Salomon hiking shoes/boots, I was unsure how these Mammut boots would fit. No B&M shops nearby stock them so it was a risk buying online without trying on. After searching the net and reading reviews, I decided to go a half size up (11.5 UK) as they are primarily for winter use and would be worn with 2 pairs of socks (a thin liner pair and thicker hiking socks). I was therefore worried when they arrived and I found I had been sent size 11 (my normal shoe size). However, I tried them on with 2 pairs of socks and they seemed to fit perfectly. I therefore went for a 6-mile hike and found them to be very comfortable (without breaking in) and to fit well. They also seem sturdy, despite being quite lightweight. I cannot yet comment on longevity or on how waterproof they are, but can conform they are true to size, i.e. whatever size walking footwear you normally wear, the same size should fit well. I was tempted to deduct a star as I was not sent the size I ordered, but all worked out ok in the end.