This is a 3HP version of the Douts module,
a breakout box for the direct outs of the TexMix. Valid for '4StereoChannels' and '4MonoChannels' version 1.5 & 1.6, for earlier channel expander versions some DIY would be required (check this).
Each module has 8 outputs so it could have 2x '4MonoChannels' connected or 1x '4StereoChannels'.
The orientation of the 8 pin ribbon cable is marked by the 'DIRECT OUTS' legend on the PCB of the channel expanders (mono or stereo) and a white line in the DOUTS input header.
DOUTS has 3 headers on the back, 2 of them are for 4 Mono Channels, the other one, labeled STEREO, is for 4 Stereo Channels.