− | File:fiberferrulesandshrink.JPG|A 2x2 mm square waveguide, 2 ferrules, and heat-shrink used to mount the ferrules and supports to the collars | + | File:fiberferrulesandshrink.JPG|A 2x2 mm square waveguide, 2 ferrules, and heat-shrink used to mount the ferrules and supports to the collars. The black residue on one of the ferrules is residual RTV that is used in mounting. |