A The tri-colour Vario plugs are a cushioning technology that adjust the damping of the shoe. The plugs are removable; incase you had not realised.
Damping systems - in running shoes - are designed to decrease force on impact and conserve energy for the athlete. They also protect the shoe and increase the durability of the midsole so that the shoe is useable for a longer period of time. While these claims are questionable - when it comes to scientific evidence - it has been proved that damping systems do conserve energy - for runners - and should increase performance. Vario Plugs were one of Adidas' first attempts at a damping system - the shoe was released for the 1984 Olympic Games - and is one of the few examples of an adjustable damping system. A modern example of an Adidas damping system is the Adidas Boost technology.