The "R" next to the curvature number refers to the circle's radius that will be formed if you stack multiple monitors of the same model together. A 1000R curved monitor, when placed next to others of the same type, will form a circle with a radius of 1000mm, whereas the radius for a similar circle of 1500R monitors would be 1500mm. Hence, the lower the "R" number of a curved monitor, the more curved it will be.