CE Tools CET103 Snap Back Releasable Chalk Line also features a 4.4:1 planetary gear ratio for fast reeling, a pinch-to-refill door design that won’t accidentally open, and a tip docking area that fit flush with the chalk line – no more loose lines! Instead of a traditional chalk line string, the Snapback Chalk Line features a polyester nylon “cord” that won’t fray.