Luffy can use Gear 2, Gear 3, Gear 4, and Gear 5. Luffy has consumed the Gomu Gomu no Mi, a Devil Fruit that grants rubber properties to the user's body (in fact, the real name of the Fruit is ...

Gear Second specifically is a very intriguing ability that Luffy copied from the CP9 members. Essentially, Luffy saw the members of CP9 move at blinding fast speeds using a technique called Soru.