The  Irwin Strait-Line Mach 6 came out in 2008 with a 6:1 winding speed ratio that made it the fastest on the market and set the standard for construction chalk lines. Looking to stay on top of the market, Irwin has revamped the Mach 6 with a wide-opening flip top that makes it easier and faster to fill the chalk box or untangle the line. This flip-top can be locked and unlocked with a simple quarter turn, and it's constructed of the same impact resistant aluminum as the body.

Like its former incarnation, the new model comes with a 100-foot, high-tensile-strength line and wide-prong hook, and includes the EZ Access Door that lets a user remove the back panel with a Philips-head screwdriver for spool changes and line cleaning. The suggested retail price remains at around $13.