CryptDisk.4h is a virtual disk based encryption tool that runs under Windows. CryptDisk.4h uses a file as virtual logic drive and mounts it as a real one, everything you write to the created virtual disk will be encrypted transparently, virtual disk in effect is a drive volume that is loaded once you have input the correct password.
Features:

Creates a virtual encrypted disk within a file and mounts it as a real disk.
Decryption is automatic, as data is read from the hard disk or usb token, CryptDisk.4h automatically decrypts the data before it is loaded. When data is written back to the hard disk, it is automatically re-encrypted.
CryptDisk.4h uses two of the most proven encryption algorithms: AES-256, Twofish-256.