FREE BONUS WICK + Regin S221 Refill Replacement Wick 6-Pack. 7 wicks for the price of 6! Use with Regin S220 Smoke Pen. Test airflow patterns, exhaust hood function, air leaks around window & doors.

Previously, my AC couldn't keep the house cool if the temperature outside was above about 90F. Even if the house was 68F at sunrise, the AC would need to kick on (set to 72F) by about 10am, and by noon it would stay on the rest of the day while the temperature indoors slowly creeped up.After spending a whole day using these smoke pens to plug all the significant air holes in my home, the temperature stays below 72F until about noon, and the AC has no problem at all keeping it at 72F even when the temperature outside is up to about 105F. Amazing how much more efficient you can be by just plugging all the holes in your home.METHOD: you don't need a pro to do this. Assuming you have a good-sized and powerful square fan, you need to find the smallest window that it'll fit in. Then just shut all your windows and doors, except that one. Face the fan outwards, so it's blowing air out, and use cardboard to close any gaps in the window around the fan. Then turn the fan on full blast, blowing air out the window. This creates "negative pressure" in the house, and air will come rushing in all the holes that exist in your home. Some are really obvious: space around exterior doors (especially the huge garage door if you have one); space around sliding windows and patio doors; any cracks in your walls (especially if you live in an earthquake zone!). Use the pen to find such holes, and plug them somehow. Masking tape can work, but also stuffing Saran (plastic) wrap into bigger holes. After spending a few hours doing this, my home was able to keep up above 90F but I suspected I could do better. A spent a second day about a week later doing a second round of fine-tuning. For example, even electrical outlets leak air!! Yes, those three tiny holes where the prongs go into the wall... behind them is the space between your interior and exterior walls, and those tiny holes leak air! So I plugged unused sockets with the "safety" plugs that are designed to keep babies from putting screwdrivers into the electrical sockets, and put masking tape around the *edges* of the socket covers--almost all the socket covers in my home were leaking. I also did a second round of sealing the spaces around doors and windows. It's amazing how many tiny leaks you can find once the biggest ones are plugged.A few days later the temperature hit 105F in the afternoon and my AC had absolutely no problem keeping the house at 72F, and it wasn't even on all the time.Seal your home like a spacecraft with these smoke pens! (Well, not quite, but it's cool. Will probably work just as many wonders in cold climates.)

Helped find the vacuum leak in the radon seal.