Product review (5 stars): Excellent step up from the original OEM-installed kit - appears to overcome plastic fatigue/wheel clip failure
My original Kenmore Elite upper rack adjuster was constructed entirely of plastic components.  They functioned for 18 months before the wheels that  are inserted in the extender arms fell off because the plastic clip on the plastic adjuster fatigued unreasonably early and failed, losing the tines that hold the wheel in place.

This adjuster kit is constructed with a lot more metal and the mounts for the wheels appear to be much more substantial and built to last.  The installation was straightforward - you just twist the main bracket into the 4th slot from the rear of the rack, then twist in the two mounting clips into which you slide the two mount points of the metal component.  Then you construct the interior plastic piece which holds the entire apparatus in position on the rack by sliding in the metal insert.  The thumb button adjuster is inserted so the button is on the side of the apparatus nearer the front, and snap in the cover on the outside, affixing the entire structure in place, and screwing two T20 STAR screws to finalize the fastening.  The package includes a Phillips to T20 adapter - but in my humble opinion, it is inadequate to safely torque the screws to place - get a bit and use a low-torque setting on an electric driver.