The Adjustable Flex-Arm allows you to adjust the forward lean of your Apex Ski Boot into 4 different forward lean positions: 10°, 12°, 14°, or 16°. A tool to make this adjustment (an Apex hex wrench) is included with each pair of boots. You can also use a hex wrench of your choosing to complete this adjustment. Please view the instructional video here: https://www.apexskiboots.com/video-gallery for further information.