THE ICY BOX IB-RD3662U3S
The aluminum casing of the IB-RD3662U3S is quite compact (for a dual 3.5" drive enclosure) and measures 204mm in length, 145mm in height and 80mm in width.
To open both bays you need to release the ramps by using the buttons at the top (right beneath the HDD activity LEDs).
Since the IB-RD3662U3S has a very convenient trayless feature you just need to push the drives inside and then secure them by raising the ramps.
At the rear we see the 60mm fan, On/Off switch, USB 3.0 and eSATA ports, mode selector and the DC-IN port.
IF for any reason you'd like to swap the default fan you can do so since the fan can be easily removed as you can see from the above picture.