The profoto d2 duo kit 10001000 contains 2 d2 1000 heads along with a convenient carry case with a flash duration of 150 000 of a second and the ability to shoot up to 20 flashes per second the d2 1000 is the worlds fastest monolight versatile and super fast they feature intuitive interfaces and the ability to adjust the power in 110 f stop increments ideal for creative photographers