The safe & sound nit comb can be effective in detecting the presence of head lice and can be used in the 'wet combing' method of treatment.For chemical treatment using rinses or locations it is recommended that the advice of your preferred local healthcare professional in sought.Head lice are small insects roughly the size of a match head when fully grown and usually gray or brown in colour. The eggs are laid in sacs known as nits stuck to the base of individual hairs and are dull in colour.The eggs take 7-10 days to hatch and the empty sacs being white and shiny may be found further along the hair shaft as the hair grows out. The lice take 7-15 days to reach maturity whereupon reproduction can take place.