Lange Rx 120 Ski Boots 2015 - Men's - Black/white A Flex Index of 120 provides a stiff feel for a high performing boot. The Lange RX 120 ski boot is perfect for advanced skiers who need adequate responsiveness to facilitate fast and aggressive all-mountain skiing. Last 100 Flex index 120 Power strap Elastic, 45 mm The Lange RX 120 uses a Polyether mono-injection shell and cuff to give the boot a lively feel with the maximum amount of rebound. 4 micro adjustable extruded Alu buckles help create a secure closure.