Thermacell Patio Shield Mosquito Repeller

I have several of these units and can't say enough about how well they keep mosquitoes and gnats away. I do use 2 units for my 20 x 12 foot deck. Manufacturers always tend to over exaggerate the effective range on products like this. I use the half rule. If it says 15ft range I assume its going to be 7 maybe 9 feet which is why I use two units at the same time. If the bugs are really bad I sometimes add a 3rd unit but they do keep the bugs away. It's important to realize that you should turn these on and place them outside at least 15 minutes before you enter the area. This is actually what the Manufacturer suggests anyway. They do take time to heat up and for the vapor to start coming out of the units and to spread around the sitting area. As for the blue pads, I hear some complaints they turn white in less than 4 hours. Turning white doesnt mean its not working. The oil is still being emitted even when it turns completely white. In fact just having them in the sun and humidity will make them turn white but it still takes about 4 hours to exhaust the pad. One other thing to note is once you open the package the clock starts ticking. If you used it on day one for 2 hours and then don't use it for a couple days they will have dried out and no longer work and a new pad needs to be inserted. With that said its not the greatest if you just plan to sit out for an hour but they are still the best solution I have found. I ordered the rechargeable unit that uses a liquid cartridge instead of the pads to see if these are better for shorter usage times. I'll update this review once I try it. Update on Rechargeable version with the liquid cartridges... This is the way to go! Theybwork just as good as the butane models with the pads. They actually heat up faster too. When I'm done with them I turn them off and they are good to go even days later since the liquid doesn't evaporate from the wick. No pads pads or butane cartritges to deal with. When repellent cartridge is empty just drop a new one in. Couldnt be simpler. Note! The cartridge that comes with the unit is only partially filled, just like when you buy a new printer. The replacements are completely filled.