Dooly* Runners - 4" This dual carbide runner has two single runners mounted to a steel plate, producing a total of four contact lines on the terrain (when paired; sold each), These 60? carbides reduce darting as they carve through existing grooves from single runners and spread the pressure across two points, extending the life of the runner and easing steering, When turning, only one blade per dual runner will contact the terrain, acting like a pair of single runners, Some skis may require drilling an additional hole