If you've never had a SiDi then remember the phrase "you get what you pay for" this is a replacement for my last pair of 5+ years. Indoor and outdoor race training in all temperatures all year round in the mid-Atlantic. They fit exactly like the previous pair and note that they should be snug, from heel to toe the strap isn't a boa but it mentions that it's similarly precise and will take some getting used to. This is a huge investment that I have made before and am happy for the second time.