The listed difficulty value of Simone Biles’s Biles II vault is 6.4.
The Biles II is a Yurchenko-entry vault followed by a double-piked salto backward. It is one of the most difficult vaults in women’s artistic gymnastics and is named for Biles because she was the first woman to complete it in competition.
Biles first unveiled the skill at the 2021 U.S. Classic. It was initially assigned a temporary difficulty value of 6.6 when submitted for the Tokyo Olympic cycle, but the value listed after its official competitive debut was 6.4. Biles completed it at the 2023 World Championships in Antwerp.
The Biles II is easy to confuse with the similarly named Biles vault. The original Biles is a half-on, forward-layout vault with two twists and is listed at 6.0. The Biles II instead uses the Yurchenko double-pike structure, which is why it carries the higher 6.4 value in the cited listing.