I bought a Bel STI off of ebay knowing I would probably have to send it in at some point for upgrade/calibration. When I received it I realized it was made at the beginning of 2006, and needed the 33.8 fix as well as a good going over. I put it in my car and within five minutes it gave me the service required notice. I contacted the seller and he refunded me $60 to have it serviced. I got it back from Bel and the card that came with it said they replaced the antenna, calibrated and updated the unit. I was excited about it until I got it back in my car and withing five minutes it again said SERVICE REQUIRED. Son of a bi==h was I mad. I called them and they emailed me a prepaid label and I sent it in for a second time. Here is the part that is pretty amazing. I got it out of the box today and the card that came with it said changed out unit for new one and tested. I looked at the serial number and it said 4810. I was shocked and quite pleased. I had the most up to date unit and brand new and I didn't have to pay $80 for the TSR, which the previous unit did not have. I went from a 0606 unit to a 4810 unit for no cost and all without asking. I just wanted my detector repaired. What a great experience with Bel's customer service. I am definitely a fan for life.