I bought this buckle from someone on this forum a few years ago. I no longer need it, so am selling it for $30 shipped.
It's basically a normal seat belt buckle, but with the center portion cut. This allows it to work with the child safety seat bar, which turns off the passenger side airbag.
So if you have the bar under your passenger seat, where you can connect the crazy expensive Porsche child seat, but don't want to shell out all that money for the Porsche child seat, you can buy this device and use whatever child safety seat you want.