It is brought down in many Jewish sources that it is praiseworthy (perhaps obligatory) for a person to read "Shnayim Mikra V'Echad Targum" (SMVT) each week. In short, it means reading (over the course of the week) the weekly Torah portion twice and the Aramaic translation/commentary by Onkelos once. While my own record in this regard is so-so at best (as a Ba'al Kriah I never miss shnayim mikra. It's the echad targum that I'm not always so good about), it is, IMHO a good practice.
That doesn't mean, of course, that it can't become the source of nonsense.
Most chumashim that are sold in Judaica stores have the Onkelos translation/commentary already contained within the volume. Thus, a person can go to almost any Orthodox shul and easily be able to read SMVT. Just about every Orthodox home has a chumash with the Onkelos in it. If travelling, a person could easily carry a chumash with the Onkelos translation in it -- there are hundreds of different types available on the market to choose from.
And yet, someone felt the need to publish a special volume for SMVT. I actually saw one in a shul in my neighborhood recently. You might ask what is a SMVT volume? Very simply, it writes each verse out twice followed by the Aramaic translation. See the sample below.
Can someone please explain to me why this is necessary at all and why a regular chumash with Onkelos just won't suffice? About the only benefit I see is that you don't have to keep your place in the Onkelos as you would with a standard chumash -- but come on! And even if that's the main draw, is there anyone so lazy that upon finishing reading a verse, they can't just go back and read it again without having it printed in front of them again?!