Up for sale is my Combro Chronograph with the serial interface to connect to a computer. This unit is great for getting quick confirmation of gun adjustments without having to set up a big Chrono or one you have to shoot through. Just strap it on your barrel and line up with a drinking straw or a dowel. You will need a USB to serial adapter to make this work with current computers. I used this model successfully. The software can be downloaded here. I used this extensively before getting a LabRadar. Price is $50 plus shipping to CONUS. PayPal F&F. I will remove the batteries for shipping. The manual for the unit is online here http://www.chronoscopes.info/manual/index.html.