The slim-format Sheaffer rollerball refill in medium point and blue ink. This is the narrower of Sheaffer's two rollerball refills and it is the one you need for the VFM, 100, 300, Agio, Intensity, Sagaris, Taranis, Valor and Prelude Signature - not to be confused with the fatter Classic refill, which fits the standard Prelude and Legacy Heritage.
Genuine Sheaffer, so the ink flow is what the pen was designed around.
