I ordered the left-hand rail for the drawer, plus the screw and the roller. The “left hand” is determined by opening the frig and peering inward, the rail on the drawer I needed was the one on my left. Pretty obvious until you start to think about it too much!
Anyway, I noticed some complaints about the screw being tough to thread into the plastic roller for mounting because it was not “pre-threaded” and because the Phillips head provided was a tough fit for a normal Phillips #2 screwdriver.
So I used a regular small drywall screw I had in a junk drawer and gently drove it into the wheel to accomplish a pre threading without stripping the original screw. Once I did this, the factory screw went right in.
The whole job took 5 minutes.