Aluminium fanless CPU cooling design
Five serial port openings (optional serial port cables)
Optional 120W or 150W external power adapter
Compatible Asrock motherboard
   IMB-148 and IMB-151

Material Aluminium with anodized black
Panel material Aluminium
Motherboards types Thin Mini-ITX
Motherboard support Asrock IMB-148 and IMB-151
Dimensions 240 x 204 x 48 mm (W x D x H)
Internal bays one for 2.5” HDD (max height 9.1 mm)
Antenna fitting holes 2
Serial port openings 5
Security Kensington lock
VESA mounting Support
Front panel USB 2.0 ports 2
External AC power adapter 120W or 150W
Product code A-ITC001-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.