Mountpoint Volume Manager is a collection of scripts that work with HAL to manage USB removable devices by automatically mounting/unmounting these devices and dynamically creating their mountpoints.
If not activated by default, this feature can be activated by Zenwalk Menu bar (Accessories > Thunar File Manager > Edit > Preference > Advanced > tick Enable Volume Management). Click on Configure if you wish to customize/manage removable drives and media.
When you insert CD/DVD, USB, SD cards etc, a new mount point should be created automatically on your desktop.
If you want to mount USB for example, you can just click on the icon. If you want to unmount for removing safely your USB, you can do so by right clicking and choosing 'Unmount Volume'. This is to make sure that all your data are saved properly on the device.
Similarly, you can mount CD/DVD by clicking on the icon, and if you wish to eject your CD/DVD, you can do so by selecting 'Eject Volume from the right click menu.
NOTE Mount points for CD and DVD can be found under the /mnt directory, whereas, mount points for other media format, such as USB, can be found under /media.