This Rasengan is Koga's favorite move. In his regular form, it is only slightly larger than an Ōdama Rasengan, however, he usually only uses it in his jinchūriki forms where it can be several times larger than himself. He wanted to mimic the Sage Art: Super Great Ball Rasengan, though not having Sage chakra, Koga found a way around this by infusing his Rasengan with Nine-Tails chakra to make his Rasengan of similar size to the said jutsu.
Because this jutsu can vary in size, the chakra required to use it also depends on what size he creates it upon use. This jutsu has been shown to charge fairly quickly, possibly because of the Nine-Tails chakra, possibly because of Koga's chakra control, or both.