Reviewed by Christine - 23rd Oct, 2018 Excellent I have been using these for years to protect me from malaria-carrying mosquitoes when on regular trips to Uganda. Switch on in my room an hour before dusk, no insects buzzing around, no bites. The cartridges only work for 6 nights, so take spares with you for a longer trip. Also make sure you take spare batteries. But well worth having the spares with you for trouble-free nights.