Product review (5 stars): fit just fine, much cheaper than from Viking
These arrived quickly and were exactly what I expected - and $15 for 16 pieces, a much more reasonable price than the dealer was asking!  Installing them should be just as simple as pushing them in to the corresponding holes in the burner grate.  But when the old bumpers fail, they often leave behind the stem that fits in to that hole, so it requires a bit of surgery to extract them.  I found a curved dental pick that worked well to dig-out the old stem and get all the rubber bits out of the hole before inserting the new bumpers.  Just make sure you clean-out the holes completely or the new bumpers won't fit properly.

Note that the 16-pack will only take care of 4 burner grates, so if you have center grates or 6 burners, need to buy more than 1 set.