These people are thieves and liars.. I wish I could leave them less than one star.. after I got to my eligibility date they would not give me a letter of compliance.. until they said I had 60 days with known fraction.. these units will blow false positives and say that you missed retest frequently in fact they make up reasons to recalibrate them when your bill is overdue.. this company is a bunch of thieves and liars run away.. it's been 19 months since I've got this installed for a one-year suspension and I am still paying for it biweekly because they will not send the letter to authorize the removal