The "V Mask" is the mask Sailor Venus wore as Sailor V. As Sailor V, she always wore this mask and hardly ever took it off. Unlike Sailor Moon's Mask, her mask couldn't see people in danger and was only there to protect her identity. She also wore this mask in her Sailor Venus form, but only a handful of times, mostly to establish that V and Venus were the same people. After Minako debuted as Sailor Venus, she removed the mask, and it hasn't been seen outside of a flashback since.
Her mask was red and was similar to Sailor Moon's mask.