Understanding the behavior of colloidal nanoparticles in submicron channels is essential for a number of technological challenges including fracture healing, channel-transport in lab-on-chip devices, lubrication in nanomachinery, etc. This necessitates the structural characterization of confined colloidal suspensions which is challenging for most conventional probing techniques. SESANS, however, probes the appropriate length scales and has the required resolution needed in such systems. It has proved to be effective in resolving the structure of spherical colloids in the channels of a diffraction grating which we studied earlier. We observed colloidal densification in the channels with the likelihood of close-packing in sheets parallel to the channel walls. In this proposal, we plan to study the effect of colloidal shape and size mismatch on the colloidal assembly in similar confinements