A Adidas Stretchweb is an outersole / outsole technology that has been implemented into modern Adidas running shoes; such as the Adidas Climachill Rocket and Ultra Boost running shoes. Stretchweb is placed on the outer most part of the shoe's sole - the part that touches the ground - and is made from a rubber compound.
Adidas Stretchweb / Stretch Web is shown in the above image; the shoe is the Adidas Ultra Boost 2015; which also features the Torsion System in the central arch of the outsole. Incidentally, the 'Adidas Ultra Boost 2015' was the first shoe to feature the Stretchweb technology. So, what is the benefit of the Stretchweb technology? Adidas state that it's purpose is to lower the amount of pressure that is generated when the foot hit's the ground; technically referred to as the 'footstrike'. Therefore, Stretchweb should lessen the impact placed on the feet of runners, increase cushion and comfort: which should lower injury and provide increased performance.