KP24 Rapid with LPF is the latest innovation in head lice treatments. The rapid formula has been clinically proven to kill head lice and their eggs in just 15 minutes, and the specially developed Lice Protection Factor (LPF) protects against reinfestation.KP24 Rapid with LPF kills lice within 15 minutes and protects against further infestation. The rapid formula kills head lice by dehydrating them rapidly and suffocating them, while the specially developed lice protection factor (LPF) inhibits reinfestation by making hair less attractive for lice to crawl upon. A metal comb is included to physically remove the lice from the scalp.