My moonlight has arrived few days ago from China. I have ordered the smallest set & cost about $30 including shipping & ezbuy shipping fee. 1st impression : reasonable quality with plastic cover for both LED & sensor unit, good enough for any occasional splashing. LED nothing special, think u can get it cheaply at SL. Time to test it. The auto ON/OFF works. It has adjustable sensitivity level but I have not tested it (don't know how anyway as manual never state). I placed the sensor sideway away from my G4 LED. This way when my G4 gets dimmer around 8pm, the moonlight will turn ON. So the trick as to when u want the moonlight to switch on is where (direction/distance) to place it from the main light source. Below is photo of my G4 & the moonlight. U can see the moonlight is ON as the LED goes dimmer. Directly shining from above, too bright for my liking : Adjust it to face sideway. Much better. Btw my tank is 422 : It has lunar cycle function BUT I am not sure if it does, just a few days into it & haven't seen the changes in intensity. In the morning, it goes off around 8-9am depends on weather!! Could be later if your tank is in a dark environment. So the sensitivity setting may be useful if it works (never test it or dk how!!!). For those interested to read the specs & Chinese as powderful as me, this moonlight is sold under Bubble Magnus brand in US & Europe. U can do a google search. Hope this simple review helps. Btw, some may ask why I don't use the G4 lunar cycle. I do but now I set it off at 12am. I don't want to overwork the G4 royal blue (impt spectrum for coral photosynthesis & u usually blast it during daytime). Afterall moonlight just for nocturnal activities, no need to use good LED. Sent from Singapore Reef Club mobile app