The STW Double Boa has the same great comfort and easy flex but now with zonal lockdown control. Dual BOA Fit System allows you to lock in your forefoot and control upper stability independently. Comfort Fit Boot Liner - Constructed With Dual Density Intuition Foam Allowing For Moderate Support And A Soft Flex, Lined With Micro Fleece For Superior Warmth And Comfort, 100% Heat Moldable For A Customized Fit Comfort Footbed - Molded Footbed Dual BOA Closure System - Dual Zone Precision Fit Flex 3/10 The STW Double Boa has the same great comfort and easy flex but now with zonal lockdown control. Dual BOA Fit System allows you to lock in your forefoot and control upper stability independently.