The Thermacell MR300 Portable Mosquito Repeller with Holster is very effective at repelling mosquitoes by forming a 15-foot mosquito protection zone just minutes after being activated. The MR300 Repeller with Holster can be used during virtually any outdoor activity to repel annoying mosquitoes, stopping them in mid-air before they come into contact with skin. The MR300 is the newest Thermacell Portable Mosquito Repeller and includes a new-and-improved holster specifically designed for optimal use with the MR300 Portable Repeller.