Buy the bowls with the blue stuff. "Why?" you ask.
Because it's not just pretty, that blue ring you see in the images is actually silicone, and let me tell you a little about silicone -
Silicone is manufactured from pure and natural silica, yes, thats right, sand. And what makes silicone so special for food grade feeding dishes is that silicone is used instead of rubber to keep the no tip bowls in place. Rubber is a petro-chemical product, so not only does it have an un-appetizing scent of petroleum, but it also wears out five times faster than does silicone. I also designed these bowls with the silicone ring to be easily removable. The reason for this is that while bonded silicone may seem convenient, the reality is that in between the bonding and the stainless steel there are grooves which trap food particles, which then inevitably create areas of bacteria. Bacteria is not good, and when its around the food our pets eat, its even worse and can lead to many terrible diseases.
Being able to remove the silicone ring and to dishwasher clean and sanitize the feeding dishes is best for your pet, and for you to have lower vet bills.
So again, choose the bowls with the blue stuff, you (and your pet), will be glad you did :)