Altras are designed to allow for natural toe placement (no narrow toe box) and be zero drop, meaning your feet and heels stay flat like you are barefoot. The Paradigm style is their maximum cushion plus Guiderail stability. These were worn for 3 days on vacation. They were making my knees hurt because I overpronate when I walk, and these appear to be made for regular or under pronation. They are so comfortable on my feet I am so sad that my knees did not agree! They were instantly more comfortable than my well worn Keds, with no break in period. For size reference, I am typically an 8.5/9, wear a 9.5 in Brooks and Hokas, and needed to size up to a 10 in these for length.