I don't think it is. look at the first (top) image in the "how to use tab of the advert.But that lense actually is a magnifying lense.
The lens is what's called a "concave-convex" (2 curved surfaces one protruding "convex" & the other recessed, "concave"). A magnifying glass or lens is either "Plano-convex" (one flat & one protruding), or biconvex (both sides protruding). Those types form a positive image & have a measurable focal length. The main function of this type is to make a distant object seem closer. (telescope, magnifying glass eyeglasses for those with long sightedness.)
The function of this "diverging lens" is the opposite, to make the close in reticule appear far away superimposed on the target.