The Siemens 6SL3261-6AA00-0VA0 is the SINAMICS V10-1 push through mounting kit for FSA frame size. This is the hardware that lets you mount the drive through a panel cutout so the heat sink sits on the air side and the wiring terminals stay inside the enclosure. It's a mechanical accessory — no electronics, no firmware — so the only spec that governs fit is the frame size match: FSA.
This kit is specific to the SINAMICS V10-1 drive family and the FSA frame. If you're retrofitting a panel that originally used a different mounting method — say, a backplate screw-down — the push-through approach changes the gland plate layout and the air gap behind the heat sink. Verify the cutout dimensions against the V10-1 installation manual before cutting sheet metal; the kit itself provides the sealing gasket and the clamping hardware.