Absolutely the worse ! Stay clear. I have COPD and after months of getting clearance from both the State and Intoxalock unit was finally approved to be adjusted. Initially before installation I asked if the lower volume would work for me and my existing condition. I was assured it would as they had “several COPD patients, Asthmatic clients and chronic lung disease drivers it worked well for”. Well guess what, it didn’t and in all honesty after over 2 hours at the garage, the unit operates the same. It does not work for me. It’s a horrible unit. My girlfriend has no issue with her lungs and yet can get the unit to work as it temporarily sees fit. The most serious issues are the retests that occur periodically and if you miss them an extra 30 days is added to your sentence. Simply because the unit works indiscriminately. Shop around ! I was Ted to share this and save someone else my aggravation.