These "PR" radiused models are built like the factory "R" series that came on many models of Polaris snowmobiles. They have a short duration first angle, radiused into what is mostly a straight angle helix (or a progressive last portion in cases of 3 angles listed). With these "PR" models you’ll usually see the distinct first angle of short duration.
Free shipping in Ontario, Canada for orders over $250 (Tires & Wheels Not Included)