I have Amprobe BT-250 and BT-120 shift sensors and use them all the time at work. They are physically identical and function exactly the same. The main difference is that the BT-120 is rated for use on circuits up to 120V [50-60Hz] while the BT-250 is rated for use on circuits up to 250V [40-70Hz]. is designed. The BT-120 includes a transmitter and receiver with an installed 9V battery, but nothing else. It might be hard to tell from the product description, but the BT-250 actually comes as a…