This is an Xotic BB preamp. It's from the hand-written serial number era, but unfortunately, the serial number has faded. The original box is included, so please check the image for the serial number that appears to be on it. It's basically a TS-type sound, but with the treble turned up, it leans towards a transparent sound. It also has a wide gain range, so it feels like you can get by with just one of these. I've cherished it, but due to certain circumstances, I'm selling it to declutter.