It includes 2 sections of rail, stock adapter and necessary mounting hardware as well as a G36 folding stock with an A2 pistol grip.

This is the plug-n-play version. No any other item needs to be purchased to make your under slung launcher into a standalone one.

For people who already have a 3D printer, you can print one yourself. The STL is available on LBRY(odyssey).
Use the included M5 bolt if another AR pistol grip is desired. Don’t use the bolt included with the grip as the bolt pattern is different. Only the pistol grips without the tang at the hand webbing area is compatible.
Included parts list: 2× rail 2.0, 1× stock adapter, 2× 3/4″ 1/4-20 set screws, 3× M5 nuts, 1×M5×30 bolt, 1×M5×35 bolt, 1× M5×70 bolt, and 1× M5 washer, AR-15 pistol grip, and G36 stock.
NOT included parts list: Launcher itself.

Benefits of this stock:

This Gen 2 Havoc 37mm launcher stock adapter will turn your rail mounted signaling device into an standalone unit. No more dead weight on your rifle if you are using the launcher infrequently.

The upper rail can be fitted with a 37mm launcher specific sight to aim for better accuracy.

Gen 2 uses a pair of longer set screws to fasten the launcher into the corresponding brass inserts in the rails. This method improves the mounting strength when compared against the Gen 1 rail, which uses the factory set screws to push the launcher against the rail.

Comparable product from competitor is almost 3 times more expansive and usually out of stock.
This folding stock adapter is available here.
https://olentangylibertygroup.com/product/gen-2-havoc-12-inch-37mm-launcher-stand-alone-stock-adaptor-full-kit/