Aluminium fanless CPU cooling design
Support one 2.5" drive bay
One serial port opening (optional serial port cable)
Optional 60W or 80W external power adapter
Compatible Supermicro Atom motherboard
   Supermicro® A1SAi-2550F / Supermicro® A1SAi-2750F
   Supermicro® A1SRi-2558F / Supermicro® A1SRi-2758F

Material Aluminium with anodized black
Panel material Aluminium
Motherboards types Mini-ITX boards
Motherboard support Supermicro® A1SAi-2550F / Supermicro® A1SAi-2750F
Supermicro® A1SRi-2558F / Supermicro® A1SRi-2758F
Dimensions 245 x 214 x 68.5mm (W x D x H)
Internal bays one for 2.5” HDD (max height 9.5 mm)
Security Kensington lock
VESA mounting Support
Front panel USB 3.0 ports 2
Serial Port Opening 1
External AC power adapter
(optional)
60W or 80W
Power connectors DC jack to 4pin ATX12V
Product code A-ITX16-M1B

The key difference is that the "A1B" version is the branded version with the Akasa logo on the front panel of the case. Whereas the "M1B" version is the unbranded version, i.e. without the Akasa logo.