|This article is about a transformation device in Kamen Rider Ryuki and Kamen Rider: Dragon Knight.|
|―Dragon Knight Transformation call[src]|
The Transformation Belt V Buckle (変身ベルト Ｖバックル, Henshin Beruto V Bakuru) (known as Advent Belt in the Kamen Rider Dragon Knight toyline) is the Kamen Rider Ryuki and Kamen Rider Dragon Knight transformation belt. When the Card Decks (Ryuki)/Advent Decks (Dragon Knight) is put up against a reflective surface, the belt appears. After the Rider shouts "Transform!" (Ryuki)/"Kamen Rider!" (Dragon Knight), the user slides the deck into the belt, starting the transformation. After inserting the deck, the armor materializes as two transparent copies on both sides of the holder then come together on them, completing the transformation.
In Dragon Knight, once the deck is inserted, the deck revolves in the buckle, giving the insignia a holographic look. A ring of light in the Rider's primary color then appears from the belt, then splits into two that revolves in opposite directions around the Rider till the armor materializes. The belts in Dragon Knight are also slightly different in that they are designed with "clamps" to "lock on" to the decks after the deck is inserted.
There is a variation of the V Buckle - designed by Hideyuki Kagawa - used by the Alternatives, based on what he understood from the first few pages of Shiro Kanzaki's notes on Mirror World. This belt was used as the Advent Master's Advent Belt in Kamen Rider Dragon Knight.
A gold-colored variant of the V Buckle is owned by Kamen Rider Odin (Kamen Rider Wrath in Dragon Knight). Also, the darkened variant of the V Buckle is owned by Kamen Rider Ryuga (Kamen Rider Onyx in Dragon Knight).
V-Buckle can be used by anyone who wields an Advent Deck. However, without a contract monster, the V-Buckle cannot be manifested unless the user is dragged by a Mirror Monster to the Mirror World.
- The V Buckle was also donned by the former member Yurika Hirokawa of Kamen Rider Girls, who represented Ryuki in the group.
- In Kamen Rider: Dragon Knight, the Advent Deck need not be put up against a reflective surface for the belt to appear. Instead, the deck just needs to be held out towards the front, creating lightning sparks which materialize the belt.
- Ryuga's V Buckle makes a deeper sound when he draws an Advent Card from his deck, but in Rider Time: Kamen Rider Ryuki, it makes the standard noise used by the other Riders.