|This article is about a/an transformation device in Kamen Rider W.|
The Double Driver (ダブルドライバー Daburu Doraibā) is Kamen Rider Double's transformation belt, a second generation Memory Driver developed for the user to link with Philip to access his abilities, and the successor of the Lost Driver in terms of belt design. Unlike earlier models, the Double Driver uses two specialized Gaia Memories at once for even more power for the user. There is only one physical Double Driver, but when Shotaro places it on him, another Double Driver manifests itself onto Philip.
Due to having Gaia Memories used retain their physical form when transformed instead of being absorbed, the user is completely shielded from their corrupting effects, at the cost of further weakening the memories' powers when not boosted during a Maximum Drive activation. As such, the Double Driver's Gaia Memories are specifically selected for various forms of combat and powers thought to be helpful in a combat situation, to compensate for their weakness against Dopants at their fullest strength.
By inserting the Gaia Memories into the respective Memory Slots (メモリスロット Memori Surotto) on their belt buckles, Shotaro and Philip can transform into Kamen Rider Double. The Left Slot holds Shotaro's Gaia Memories and the Right Slot holds Philip's. If either Shotaro or Philip equips the Double Driver, a duplicate Double Driver will form over the abdomen of the other. When Philip puts a Gaia Memory into the Right Slot, he undergoes Soul Forward (ソウルフォワード Souru Fowādo), sending his soul to Shotaro to transform both of them into Kamen Rider Double. The process causes Philip's body to fall into a comatose state. If the Fang Memory is utilized by Phillip, the Soul Forward is reversed, with Shotaro's soul and the Joker Memory transferring to Philip's body, while Shotaro's own is rendered comatose.
As long as the Double Driver is worn by both Shotaro and Philip, they can telepathically communicate with each other provided that both of them are conscious outside the transformation to Kamen Rider Double. The transformation into Kamen Rider Double will be canceled if both Gaia Memories are removed and none are re-inserted for a certain amount of time.
Another slot on the right side of the Double Driver is called the Maximum Slot (マキシマムスロット Makishimamu Surotto). When a Memory is placed in the Maximum Slot, Kamen Rider Double can use a Maximum Drive (マキシマムドライブ Makishimamu Doraibu) finisher attack. This specific slot is used for the Joker Memory to execute one of three different Maximum Drive finishers depending on Double's current form.
- CycloneJoker: Joker Extreme (ジョーカーエクストリーム Jōkā Ekustorīmu): Double's body splits down the middle as the halves descend on their target. A variation of this attack involves Double jumping off the back wheel of Kamen Rider Accel Bike Form, allowing for faster acceleration upon descent.
- HeatJoker: Joker Grenade (ジョーカーグレネード Jōkā Gurenēdo): Double somersaults in mid-air, then Double's body splits down the middle during descent as the halves each hit the target with elementally energized hooks.
- LunaJoker: Joker Strange (ジョーカーストレンジ Jōkā Sutorenji): Double splits down the middle, with the Luna half making four copies of itself, and all five Luna halves execute rapid-fire karate chops on the target(s), then the Joker half strides in close to finish the target(s) off with a charged vertical chop
In other forms, it can be used to insert the right half's Memory, allowing for a Twin Maximum (ツインマキシマム Tsuin Makishimamu) attack, but this is immensely dangerous due to the strain it puts on Shotaro's body.
During the final battle with the Utopia Dopant, Kamen Rider Double CycloneJokerXtreme places the Prism Memory in the Maximum Slot to execute the Double Prism Xtreme (ダブルプリズムエクストリーム Daburu Purizumu Ekusutorīmu) Maximum Drive.
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