Product review (5 stars): Perfect!
Perfect!  These gap covers stay in place and don't shift around like the old aluminum ones we had before.  They are easy to clean - I just wipe them down when I clean the stove top.  I have a natural gas cooktop and have had no problems with discoloration.  Have not tried to put them through the dishwasher yet and I probably won't because I've had other silicone bakeware items that got dull/cloudy after going through the dishwasher.