The Dooly&trade has two 7/16" Flat-top® runners mounted on a plate for each ski. The four contact lines on the snow surface will help decrease darting of your sled as it makes its own groove in the trail.
When in a turn, only one of the Dooly™ bars will be in contact with the snow or ice. Therefore; a Dooly™ with 4" of carbide on both runners will have the same turning power as a single runner with 4" of turning carbide.
Each Dooly™ is packaged individually.