Main feature is backup/restore to/from an imagefile and clone a disk to another.
But you can also (not exhaustive) :
-save/restore the MBR or BS,
-delete the layout of the drive, create disk, create a main partition,
-wipe with 0's,
-resize partition (negative growth works but be careful) and volume
-create a raw image file,
-make a vmdk/vmx from a raw image file to boot your cloned disk in vmware,
-turn a physical disk raw image file into a VHD file and the other way around,
-install grub4dos MBR,
-do various operations on the registry around booting,
-copy all files from one logical drive to another,
-format any device to fat16/fat32/ntfs (includig usb pen),
-read faulty devices (with bad sectors for instance),
-backup & restore from devio (imdisk server-end),
-perform speed tests,
-edit the partition table.
The drive will be locked and dismounted before reading / writing.
CloneDisk will use 64k aligned buffer to achieve best performances.
CloneDisk should handle file up to 2^63-1 bytes.