Thermacell Mosquito Repellent Rechargeable

****Update*** I still love this thing. Here is what I have learned since my initial purchase: *Use up those cartridges at the end of the year. I stored mine with a partially used cartridge but it didn't work as well in the spring. Popping in a new one made a big difference. *The cartridges are all the same size. They are filled according to the number of "burn" hours. When you get one that looks half empty it's because you didn't buy one with the extended hours. *Don't expect instantaneous results. You absolutely must allow the unit to warm up before using it. 10-15 minutes will do it. *Don't forget to turn it off or you waste some expensive formula - lesson learned there. *Make a habit of bringing it inside and charging it OR make sure to have a charged backup on hand so you never have to go without. It sucks when it shuts off right after you've settled in. (I'm about to get another unit). *Yes it works on Salt Marsh mosquitos though they did get a couple of ankle bites in at the picnic table. Not sure if the top of the table inhibited the coverage of the protection but considering I would typically end up with at least a half dozen welts (sans spray) it's still a win. Original review: I understood when I bought this, that it needs to warm up, you will see a tiny plume of "smoke" occasionally, and it may not actually cover a 20 foot radius, especially on a breezy day. That said, this little wonder actually works. Thanks to our mild winter the mosquitos are very plentiful this spring. I am tired of wearing bug spray and burning incense & candles to keep them at bay. Tonight I really had the opportunity to test this thing. I turned it on for a few minutes before settling in on my southern New England porch. While I see bugs flying around me, none have landed. I have been out here for about 2 hours around dusk without a single bite! I am going to get another as a back up and stock up on refills. With a trip to the Maine shore planned for this summer I'll putting these bad boys to the test against the vicious salt marsh mosquitos. Can't wait to sit outside by the firepit without needing bug spray.