Product review (2 stars): Now I know how the Maytag repairman makes a good living
Jenn-Air is owned by Maytag and, I assume, is meant to be higher end.  That has not been my experience with either my somewhat expensive Jenn-Air stove and Range top.  The new knobs replaced the original knobs on my range top.  The originals were cheaply made, worked loose and broke easily.  The new ones fit nice and tight, but are the same as the original cheaply made ones and started showing "play" within a few weeks.  At least I now know where to get new ones again when these break.