I am unfamiliar with Walmart helmets but any helmet that meets the CPSC helmet standard is equally good or rather not good. Initially helmets were designed to allow you to fall 2 meters without fracturing your skull. But that isn't the danger to helmeted riders. A fall of two meters is supposedly the distance you would fall in the most common falls - falling off of your bike at a stop light. If you are involved in a motor vehicle accident you usually are so badly injured that it wouldn't matter if you have a helmet on or not. Now we might call certain types of motor vehicle accidents "fall offs" as well because they are really stupid - a couple of years ago I stopped at a four way stop intersection. Came to a stop and let everyone take their turn. Then as I was almost all of the way across the intersection a woman rolled the stop sign and ran right into me. I slid right up her hood and fell off on the right side of her car. She was only traveling perhaps 5 mph and the only injuries I sustained was a smashed big toenail and the bike was a total. Now, if an accident EVER happens to you like that ALWAYS get a lawyer and do not try to negotiate with the insurance company yourself. What I got barely paid for the damages. If I had a lawyer it would have been at minimum 10 times that amount.

In any case, the problem with a bike crash is that the true injuries do not come from a fractured skull but rather from a concussion. So a CPSC helmet approval is actually a dangerous helmet though this will IMMEDIATELY bring claims that "MY HELMET SAVED MY LIFE". If your life was "saved" it was not an accident strong enough to kill you.

However, Trek did some serious research into the proper way a helmet should work. And under the their brand name "Bontrager" they market a helmet with the appellation of "Q-cell". There is not enough data to know if they really increase the safety of a helmet but I bought one and wear it because it actually has some science behind it.

But as a resume, I raced motorcycles with the American Federation of Motorcyclists (AFM) and checked out helmets since the speeds are so much greater. Well, road racing crashes aren't usually what you could call a crash but losing traction and sliding out. Motorcycle helmets have a hard shell and so the actual foam padding inside the helmet doesn't do anything, the hard shell allows your head to bounce and slide along the ground without skin damage,. When I realized that I was doomed to a perennial third place I retired and they asked me to become the Safety Director. So I went down to Bell Helmets and talked to them about their safety standards. Believe me, the hard shell was by far the most protection. And as proof, Many years later I was riding through a parking lot at about 5 mph and a first generation carbon fiber fork fell apart and dropped me on my face/helmet. I was released from the ER as perfectly fine. I wasn't and spend the next two years having no idea what I was doing. I couldn't even remember to eat. When a friend asked me to the Club dinner and while there his wife, a nurse, observed me having a seizure. He made arrangements for a Stanford neurologist to see me. The neurologist told my friend that he had never seen a concussion this bad. It took about six months to balance the medications required to stop several different types of seizures and suddenly it was just like waking up from a nightmare. Nothing made sense and it took me years to recover a large part of my memory. At first I couldn't even drive up to the supermarket without getting lost.

While it would probably be possible to make an inflatable helmet they would have to be especially "tuned' to the rider weight which makes it impractical. Part of the problem with helmets is that you cannot wear a helmet over a certain overall diameter since any larger it would block your vision which is especially important on a bicycle.

I suggest the Q-cell from a Trek Dealer and there is no reason to get the expensive version. I paid $100 for mine but a friend recently bought one for $60. So they are coming down in price. You can recognize them from the "standard" helmet by the padding looking like honeycomb.