Nits push the more flexible teeth of most combs apart, sneaking between them and evading capture. The rigid teeth of the WelComb hold tight when they encounter a nit, taking it with them as they pass by.
Precise spacing. The teeth are spaced apart at exactly the distance necessary to grab lice and nits but still smoothly run through strands of hair shaft near the scalp.
Beveled edge. The deeply slanted edge of each teeth lets you get under the louse or nit that adhere to the hair. The rounded edges of most combs cannot get close enough to the scalp and easily slide right past nits.