We buy milk by the litre.  We can buy PC by the litre too. Compucon has a small PC section with 3 PC models rated 6L, 4L and 2L (they are called Onyx, Short 1U and Pearl) respectively.  Diamond is 17L for reference and it is considered small by desktop standards (micro ATX). Pearl is the latest release.  It is so thin it can be piggybacked on an LCD screen and a bracket is provided for this purpose.  The small size does come with limitations of computational power and data storage size.  Pearl is therefore appropriate for applications that do not need high speed or large internal storage.  Otherwise, Pearl can justify its name as the pearl of PC.  Onyx and Short 1U are bigger in size.  They can have a big hard disk running a faster CPU for most office applications if you like.  This trio are commercial grade PC as against home office grade.  Short 1U is the most rugged of the three.  Please see Pearl here: http://www.compucon.co.nz/content/view/733/249/