Yes, straight-to-discount jeans are made for places like the Rack, TJs, Loehmann's, Off 5th, etc, and retail for around $120 or whatever those places price them at (so the "compare at" price is a total lie, lol). Hence the "straight-to-discount store" designation. They can get away with this because the jeans are made in Mexico and the workers are probably paid a lot less.
The style number is the longer of the 2 numbers...style numbers on S2Ds will almost always have a J in them somewhere, and to my knowledge only S2Ds have J anywhere in their style numbers. Some other tricks you can use are the combination of the brown content tag and the red size tag, the "assembled in Mexico" indication on the tag (even the older S2D pairs that have tan content tags will say they were made in Mexico), etc. Sometimes you can sense that the quality of some S2D pairs is not quite up there with the full retail pairs, but many of the newer S2Ds and a couple of the older ones are actually really nice.
