I know this thread is a couple months old, but I’ll respond anyway, as I had the same question before I got my Keto breath monitor (from House of Keto). Mine just came a few days ago. I have been on Keto diet for over a month and am quite disciplined. The meter so far is only reading 0.0 which indicates no Ketosis. 
Today I noticed my urine is smelling like asparagus again - strong, which is one of the markers of Ketosis. Tested with Keto Breath monitor again. Still 0.0. Will keep going w/disciplined diet and test in a.m. My boyfriend just got a ketone blood monitor so when I see him this weekend we will geek out and test both ways, while readings measure different ketones, they should correlate. So for me, jury still’s out! Will post update with exact readings.
House of Keto
I just got mine yesterday, so I tried it last night and it said .4
I had two drinks with white rum and probably a few too many cashews and today 0.0
I have been fasted most of the day and still 0 although my ketostix are showing .4
Interested to know how it works for you. Maybe I should have chucked out the dough and gotten the Ketonix…
It’s a cheap Breathalyzer
“May the Force (fat adaption) be with you”
IF/EF Keto WOE is Self-Discovery 
Good luck and much success in your journey in IF/EF Keto WOE 
I looked on Amazon and they updated the meter. It no longer works for ketones according to the reviews 
The Greenwon no longer works apparently which was the alcohol breathalyzer. The model was updated. I’m sorry if I wasn’t clear. Does the one you bought work pretty well? The cheaper version of an actual ketone meter? The House of Keto one? These are my first posts here so I’m trying to learn the site. And how to look back. Ok you do have the breathalyzer not the ketossis meter. I’m sorry. I can’t get that version of the breathalyzer anymore. It changed
I’ve tried it (HOK breath meter) multiple times daily for a week, including times where I’ve fasted all day. Always reads 0.0 = not Ketosis. I was at my partner’s this past weekend and he has a blood meter. I tested at .6 which is ketosis, but on the HOK breath meter still showed 0.0. While breath and blood measure differently, there ought to still be correlation. I’m going to return them.(I bought 2)
okay i’vehad the breath monitor for a few weeks, and never nothing but 0.00? what’s the reviews on this
I have 3 bought from 2 different sellers from walmart they work fine
I get best results when temp is above 60F and breathe in at count down 50 to 30 hold breath place lips over nozzle loosely and blow moderately like fogging a mirror at 0
go to your bathroom mirror and practice if you can fog your mirror you got it 
I’ve tried umpteen ways, and still come sup 0, I am going to use the strip as well for a few days again and see what those results are
i have been keto for 4 months this time round and preiously keto for 18 months. I used ketostix before. some guy on a keto forum suggested the HOK breath analyiser was a good way to check ketone levels. I ordered one and it took a month to arrive. Ive been testing my breath and its been 0.00 for 2 days. I think this analyier is a load of crap and WOULD NOT RECCOMEND TO ANYONE! do not waste your money!! its a scam. Looking at the item that came in the post, the packaging is cheap as is the leaflet. They buy them bulk cheap for a $1 from a Chinese company put their logo on it, sell it at 300% and pass it of as a workable device. waste of $30. Opportunists! so pissed off with house of keto right now i will be asking for a refund and hope they pay me for my shipping costs. very dissapointed in this company.