they do work, but it's not like it's going to avoid a deer detecting you everytime. However, if your a serious hunter you want every odd in your favor. i researched this couple year ago a lot and read on them, then i just made 1 myself, think i have about $75 in mine. There are videos on youtube that show how to make 1 so me and a buddy brainstormed ideas and put mine together and i like it. i have tested it several times w/does and hunt bait piles when i knew the wind would blow right over my bait pile and hunt it to test that. My findings i was a little in disbelief but over and over again, i would watch deer feed down wind, i would watch them for a bit and then turn it off. Yes, everytime within less than a minute of shut off they would throw their nose up, stomp around and leave like you'd expect, so they do work. I am a scent fanatic, i built a lil ozone closet and run a 500-600 mg/h generator in it with my clothes and then when i leave the house i throw them in a scent bag and dont put my clothes on til i'm in the field leaving my rig. If you use an ozone machine in the field long enough you will see several reactions to it, some deer completely ignore the smell, some lock up when they hit it and look and smell a min or 2 then go on about their biz, some lock up and dont like it and leave but dont snort and run off just unsure, but i can't think of an instance where i had 1 hit my scent cone and run off. The only thing i dont like about it is carrying them into the field and setting them up on a tree, i made a littlle quick connect bracket but its still annoying so i dont always use it. i do believe if you use it long enough tho it would be the diff in a big buck make or break, even if he steps in the scent cone your gonna get a shot before he spooks IMO. Hope this helps... theres a really good story about a police dog trained to track people and different things they tried to kill scent and hide from the dog under boxes, ozone won bigtime, worth a read.