Product review (3 stars): We made it fit
I bought this for my parents stove. It's a whirlpool and we had been having a tough time finding knobs. None of the plastic caps fit our stove but the closest one was the blue.  What i would suggest -which is what my dad end up doing -is to grab the color with the tightest, closest fit and then grab a pocket knife and carve out a bit of plastic it according to the mold and then from there is a bit of trial and error. -BE AWARE IF YOU HAVE A GAS STOVE AND HAVE NO EXPERIENCE WITH THIS BECAUSE I WOULD NOT RECOMMEND IT- My dad is an electromechanical engineer and he has plenty of experience with these kinds of stuff.
Overall the idea of the product is great and the plastic fit parts (i don't know what they are called), come in a variety of sizes so if it did not work for my stove doesn't mean it might not work for somebody else's.