The page at:

http://mms.mongodb.com/help/tutorial/restore-from-snapshot/

says:

With MMS Backup, you can restore from a stored snapshot you may build a custom snapshot reflecting a different point in the last 24 hours. For all backups, restoring from a stored snapshot is faster than restoring from a custom snapshot in the last 24 hours.

There seems to be two sentences mashed into the first sentence there?