The Cloudboom Strike 2 is On's marathon racer rebuilt with its athletes: a new CloudTec Sphere cushioning system and dual-density Helion HF hyper foam surround a curved carbon Speedboard that is both lighter and stiffer than the first Strike's. At 191 g in unisex sizing it sits right in the super-shoe weight class.
It suits you on the days that count — half marathon and marathon race efforts, in the shoe On's elite roster wears — and both generations stay on sale, so the original remains the cheaper way into the platform.
It is not a trainer, and On's softest race foam earns its low mileage budget. The Cloudboom Max exists precisely so this one only comes out when there is a number on your chest.