While working on our hybrid lineup for 2012, we aimed to create the thinnest, most flexible boards on the market. In doing so, it became apparent that we would need to use a thinner insert bar (depth wise). We quickly realized that we were limited to what we could do with a standard 1/4-20 bolt insert because we couldn't get enough turns with the mounting screws into a thin insert bar. The logical step was to use a bar with metric inserts. Metric threads are closer together and hold better with using half the depth of a 1/4-20 screw. Using a metric M6 insert allowed us to have the most secure binding to board interface ever. Bottom line, it's a better connection! Instead of limiting this advancement to our hybrid boards, we decided to put a metric screw insert pack into every one of our 2012 boards. you can be guaranteed that no matter what new LF board you buy, you'll have the most advanced and most secure system available!