Testing video found here (please note, PAR measurements at depth of 3" were out of the water). The Twinstar 900E that was tested is version 3. This metal fixture is very sleek with thick acrylic cell cast mounting arms. This is not adjustable so you cannot lower or raise the light. The light is only on and off 100%. You must buy the dimmer for dimming functionality. This light is extremely powerful with PAR of 117 at 18" deep! This means for the UNS 90P (~18 inch deep), you'll have more than enough light (maybe too much when subtracting substrate height). In addition, this fixture is also very effective for the UNS 90U which is ~22 inch deep if you have 2-3 inches of substrate. Since PAR of 50+ is considered high light, you may want to get a dimmer for this fixture.

PAR tested using Seneye PAR meter unless otherwise noted in the notes section. Testing process is documented here