@@centipede9292 which one you advice me to buy ??? 260x or challenger 4. I Run 5 to 10 km 3 times per week with pace 5-6min/km.. I have (adidas adios pro 2- saucony endorphin speed 2 - asics novablast- nike pegasus turbo - brooks caldera - hoka clifton 6 - nike vomero 13 - hoka clifton 3)