These are the competition friction rings with the curved slots in sizes to fit Brembo's aftermarket GT kit hats. They're bundled with better pads and fluid as a kit.
Expect the kit to cost in the range of $2,000 to $3,000 or so.
For track day use, you shouldn't expect to see a benefit over the regular friction rings. As far as the pads are concerned, if you like the Brembo pads, just buy them separately. Ditto the fluid.