3,5" is the most compact standard form factor for embedded SBCs. Fastwel' products are fanless, robust and have wide range of functions on a very small footprint.
Intel Atom E38xx-based SBC with StackPC Expansion Connector in 3.5” Form-Factor
СPB905 is a 3,5" single board computer based on AMD LX800 (500 MHz) CPU with PC/104 support (32-bit PCI and 16-bit ISA).