These work very well. So, why only 4 stars? Well, as some have pointed out, they become very difficult to blow through after a fairly short time in use. Some have suggested placing some cotton balls in the blow end, removing them when the unit begins to clog up. That’s a good idea, as the way this actually works is 2 fold. It has both a paper fiber air filter, similar in appearance to the automotive air cleaner filters of yesteryear, and after the smoke passes through that, it is then passed through activated charcoal. From my experiments with making my own filters, I can attest to the fact that it’s the paper filter that actually removes the visible smoke (resin), as filters I’ve made that used activated charcoal only, even when constructed to route the smoke efficiently & evenly through all of the charcoal, don’t remove visible smoke, at all. So, it would seem that the charcoal is there only to remove smell and possibly any drug elements, such as THC, or nicotine. So, by placing the cotton balls in the blow end, they begin to absorb most of the resin, which is what is making the smoke visible, preventing most of it from getting to the internal paper filter. But, even this method will eventually clog the paper filter element within the unit. There is a solution to this. I take a bottle of 99.9% Iso Alcohol and place it in a deep kettle of water - water as hot as I can get it from my tap, to heat the alcohol up. WARNING - NEVER USE FLAME OR THE STOVE TO HEAT ALCOHOL, UNLESS YOU LIKE SERIOUS BURNS! After the alcohol has had time to become heated, it is then poured slowly, a bit at a time, into the SmokeBuddy. As it will take some time to break through the resin, it won’t take much to fill the unit to the top. At first, it will just sit there. But in a minute, it will begin to flow out the bottom, and it will have a ton of resin in it. I do this over a large bowl. I pour about 8 ounces through the unit. I also use a paper towel to dry off any spilled alcohol at the rim, so I can put my mouth on it and blow the alcohol through. But, it’s important not to do this too soon, as the heated alcohol, being allowed to flow slowly, will absorb more resin then blowing it through. The blowing helps clear out the last of the alcohol, and I only do it after each pour stops running out the bottom, to clear it out for the next pour. You can’t pour in too much at a time due to how slowly it flows through. Try not to overflow it. Once this has been done, leave the unit all day to dry out the alcohol. Blowing through it from time to time will help. If you desperately need to use it before it dries completely, you can, but I try to avoid it. When it’s finished, it will flow almost as well as it did when new, and so far, I’ve not yet been able to use one up to the point that I can’t re-clean it. I’d have given it 5 stars, if the maker had cared enough to make it out of metal, and so that you can unscrew the top to change the paper filter & even replace the charcoal, when needed. Instead, they’ve elected to have us contribute more to pollution, as people will be throwing these plastic bodied units into the trash when they no longer work. As I said, they should have made them out of metal. They would cost more, but they would last forever, with only the filter elements being repurchased and replaced as needed. Far better for the environment & for the customer. There are just WAY too many disposable items being made and sold these days.
