Here's the description from the Sadowsky site:
Sadowsky Guitars is pleased to offer the new Sadowsky Onboard Bass Preamp. Completely prewired control assembly offering the same controls and preamp as all Sadowsky Basses.
VTC=Vintage Tone Control (pull up bypasses preamp)
Can be installed with included control plate or transferred to other plate or pickguard.
Can be installed through a rear control cavity either 4 in line or diamond pattern.
Pickups attach via connectors at pan pot.
Direction of the pan can be easily reversed by switching connectors.
Installation requires a side jack and a battery compartment.
We recommend shielding the control cavity at the time of installation. We recommend installation by a professional guitar technician or builder.
This system is not compatible with EMG or any other active pickups requiring anything other than a 250K or 500K volume pot. For these applications, please custom order a parts only preamp kit and use your existing volume pot.
This worked great, but I already had a Sadowsky preamp DI pedal which did almost exactly the same thing. I only used this for about a month before I went back to my J-Retro Deluxe and if I ever get the jones for the Sadowsky sound I can put my J-Retro in passive and use the Sadowsky DI.
This thing works great. Just as advertised. Super easy to install.
NOTE: The only thing different about mine versus dead new/stock is that I cut the power wire in order to splice in the leads to connect to my bass' built-in battery compartment.
These are $269 new plus shipping. I'll take the first $200 plus shipping.