The quality guaranteed double-sided flea comb is used to find and remove fleas. Before using, groom your cat with a comb or brush to remove mats and tangles that could damage the teeth of the flea comb. If needed, apply flea treatment before combing. Comb slowly, periodically checking the teeth of the comb for fleas or debris. Between strokes, dip the comb into a cup of water with mild detergent to kill the fleas left on the comb.