Let me preface this review by saying my experience with Smart Start is via a borrowed vehicle to deter all of the "serves your right" from uninformed commenters. My mother has the SmartStart interlock and today I was forced to borrow her car. The first start of the vehicle today, August 12, 2015, took 24 attempts with various codes... "blow harder", "blow softer", "hum louder", etc. I am now stranded at my office after 41 attempts to start the vehicle. The module overheats apparently and is rendered completely useless. If you at all have a choice please go somewhere else allowed by the State of Texas and steer clear of the antique units they provide at SmartStart East. I have looked into other options and discovered the necessity for humming into the machine while simultaneously blowing has been completely obsolete since long before the system was installed by SmartStart. Please stay away at all costs.