"A cheap, portable fix for ergonomics, provided you bring your own keyboard."
The "0.79" to 4.72" height adjustment" means it can raise your screen between one and five inches. This is enough to move the screen from desk-level to a more comfortable eye-level for an average person at a standard desk.
This is for the mobile worker who needs a cheap, light, and compact way to improve posture on the go. It makes sense if you already carry and use an external keyboard and mouse.
Users who type heavily on their laptop's keyboard should avoid this, as it will likely be too wobbly. Anyone with a heavy 15.6-inch laptop, particularly a gaming or workstation model, should invest in a more substantial stand.