You are looking at a set of Uprated Tensioner bearings (replaced 145807 and 149791)

These bearing are up-rated and of a better quality that the factory bearings.

Only sold as a set, one set would be both bearings.

Notes:
Outer Bearing carrier weight 128 grams. Stock bearings weighs 220 grams.
Load rating of the uprated bearings are 17,920 Newtons.
The stock bearing load rating is not disclosed by SKF, but during the development stage, we determined the stock load rating of 10,240 Newtons.

The Newton is a measurement of force.

1 Newton = 0.224809 pound (lbf)
7,920N = 4028.5 pound (lbf)