Hedrin Head Lice Detection Comb has been specially designed for the detection of lice. It has been clinically tested and is designed to be accurate and comfortable to use. The size of a head louse can vary from a full stop . to the size of a sesame seed. The comb have been specially designed for detecting lice and the nits (empty eggs) The comb is made from tough ABS (Acrylonitrile Butadiene Styrene) and the teeth are precision engineered so they trap the lice and will not bend in use.