Oregon ripping chain. Ripping means that the file angle is only 10 degrees. This cuts faster in quarter-sawn wood. When cutting quarter-sawn wood, there is no need to cut through the fibers at the end grain, which is why the standard file angle is 30 degrees. For quarter-sawn wood, 10 degrees or even 0 degrees is better. The advantage is that every other tooth on this chain can be sharpened down or removed.
3/8 Oregon 1.6 mm.