VRegulator 6.0v

The V-Regulator is a compact, high-performance voltage regulator which is ideal for any model where standard servos are to be operated in conjunction with a Lithium battery. In this way fairly small to medium-sized fixed-wing model aircraft and helicopters can be equipped, or re-equipped, with modern battery technology.
The signal wire is looped through from the input to the output, which means that even a single 6V servo can be operated in a model fitted with a high-voltage system.

A single 6V (Japanese say 4.8v) servo can be operated in a model fitted with a high-voltage system.
A further application is for those electronic ignition systems whose maximum power supply voltage is limited. The regulated output voltage ensures that servos give a constant performance.
The unit effectively filters out servo feedback currents.

Also 5.3v available