PIC 10 Pack Mosquito Repellent Coil. It repels mosquitoes and each coil burns for 5-7 hours outdoors. For best results, use in a confined area, on patios and porches. Place 1 coil every 10'. Contains a proven formula of Pyrethrum. Each coil lasts up to 5-hours to 7-hours Comes with reusable metal stands. Mosquito Coils help repel mosquitoes in confined areas outdoors. It is useful in places where there is little or no breeze such as patios and porches. Do not use indoors and see packaging for additional instructions for proper use. Coils repel mosquitoes that may transmit zika virus and are effective when positioned every 10 feet.