The On-Site Standard unit is a 3.5 inch hard drive with a power unit.  This unit is use for desktop computers and laptops where being able to power the unit from the USB port is an issue.  If your laptop is an older laptop, over 5 years old, then this unit is recommended.  Below is an example of what the unit would look like.  

The On-Site Slim unit is a 2.5 inch hard drive without a power unit.  This unit is use for laptops where being able to power the unit from the USB port is not an issue.  If your laptop is 5 years old or newer, then this unit is recommended.  Please make sure your USB can support the power required by a USB unit being plugged in.  Below is an example of what the unit would look like.

This unit is also available in a One Touch backup unit.  See example below.

For our Corporate customers that have massive data requirements and redundant requirements, we have several RAID solutions to fit your needs.  Click Here to see example.