Question about tennessee walker bits?

tomorrow i'm going to a walker auction and i've been searching on different tack to get and i keep seeing this walker bit, it's obviously different from your typical bit. so is it necessary to use a walker bit on a walker? i know it all doesn't really matter what kind of bit as long as the horse responds well to the bit. so how does the walker bit differ from your typical bit with shanks, what makes the walker bit best for walkers?