With the FX Panthera front bottle drop down adapter from Saber Tactical you can equip the FX Panthera/Dynamic PCP air rifle with a second air reservoir or you can move the reservoir of the stock forward.
That reservoir comes on the front of the air rifle, where due to the design of the Panthera there is normally no space left and you will have to remove the rails.

This drop down adapter, which you place at the front under the barrel, lowers the air reservoir so low that it can even be used in combination with the Arca Swiss rails of the Panthera.

The Saber Tactical FX Panthera front bottle drop down adapter is made entirely of stainless steel.