Here's what other sites are saying:
Garmont's Radium Thermo features their overlap design. The overlap shell follows the anatomy of the foot and lower leg for crisp, precise downhill performance. At the same time, the design eliminates the restrictive tongue to allow more independent movement between the cuff and lower shell. In the touring mode, the instep and foot are nestled comfortably and securely so the boot and foot stay in contact.