For general downlight applications that demand high efficiency, superior optical control, and a square aperture shape is preferred. One piece trim eliminates mitered flange corner joints and inside corner gaps. Patented Bounding Ray optics provide high efficiency, and superior lamp shielding. Optional concentric glass lens available for low-angle shielding. Patent pending rough-in design allows 1/4 adjustments in all directions and up to 5 degrees of rotation allowing post-installation adjustments to ensure consistent trim-to-trim alignment. After alignment is set, trims lock into place so that alignment is not disturbed by maintenance or re-lamping.