[Original message of the thread has been deleted. It was posted by a spam bot which replicated an old message about UPS boots. Three months later it edited the contents to post some ads and links about women's lingerie]
Hello lamxuyen,
welcome to the Forum.

You will find some more information at alpinecarving.com (see at "Links" on our Homepage)
There is written:
•Older models: ◦The RSV Mach, RX Mach, and Mach X boots do not have a buckle high up on the cuff, and do not have a power strap. So, you really need to add a power strap for these boots:



Mmh, could be a possibility, but Mach X are now very old now.