Keson Giant Double Box 
                   * Two boxes strung together so workers don't have to run to re-chalk the line. 
                * A great choice for roofers, sidewalk and parking lot layout---
                  anywhere there's a lot of walking back and forth. 
                * This box increases safety on roofing jobs.
                * The string in this box is 1/8" polycord and it also features the BigMouth chalk fill system.