NOTE only the weld in adapters are available.
These adapters allow the re-gassing of the hydragas sphere fitted to several cars from MG/Rover including the MGF.
Re-gassing does not return the car's suspension to a "as new" condition as the servicing of the internal valves is not possible nor does it take any account the condition of the other components in the suspension such as the knuckle joints,pivot arm bearings or the shock absorbers, so consider this as a temporary repair as the majority of hydragas spheres are past their intended service life.
Despite claims by 're-gassers' this will not return the suspension to 'as new' condition.As mentioned above there are a number of components that make up a suspension and any MGF will have tired old components. 
Regassing is only a temporary fix.The very last MGF produced (2002) will now be over 24 years old. Beware when re-filling the system with fluid it requires a vacuum pump to remove any air from the system before re-filling. Using a cheap 'Ebay' pressure pump will not do the job correctly as recommended in the workshop manual.
These adapters allow the fitting of the high pressure nipples (not supplied) and need TIG welding into the top of the hydragas sphere.
The high pressure 1/8" BSP valves are readily available from Ebay.
A set of 4 adapters are £30 plus vat. Shipping UK is £5 EU is £9
I also have a limited number of the mechanical fixing type using a riv-nut.
These require a heavy duty set of riv-nut pliers as the riv-nuts are a high tensile steel variety. The kit comprises of 4 stainless steel adapters that screw into the riv-nuts. These are supplied with O rings to seal them but also require PTFE tape (not supplied) to seal the threads. The high pressure valves are not supplied. 
To eliminate the issues with hydragas suspension you can swap out the hydragas for a FCCKit (coil conversion kit) see on MGF suspension pages.