Bests & Worsts Reviews from Amazon

*UPDATE 2014-06-16* I bought another one last week, and the instruction that comes with the unit has all the latest information. It says this about the Random Setting: * When the timer is at clock display status, press and hold HOUR button for 3 seconds or more to turn on or off the random function. "RND" will be shown in the LCD when activated. * Random function is only valid for the programmed setting time period. * Random ON/OFF time generally will be 2-30 minutes postponed based on programmed setting time. If programmed setting time duration is below 10 minutes, RND will be shown in the display, but in fact, it is not valid, the appliance will be switched ON/OFF as per programmed setting time only. Disregarding some grammar weirdness, I think it's fairly clear, although I still wonder if it'll postpone things past the OFF time. For example, if ON at 10:00 and OFF at 10:10, will it start as late as 10:30 and end as late as 10:40? I'd guess so. Obviously, if OFF is set to 10:09, random function won't take effect because the duration is only 9 minutes. --original review below-- The manual it came with only describes the old model (15150), even though it states both model numbers (15150 and 15154). Note the old model doesn't have "random" and "DST" features. I had to search the web, cross-reference with other models, and experiment to figure out how the "random" feature works. First, you can toggle "random" mode by pressing and holding HOUR/RND button for 3 seconds. A tiny (RND) indicator is visible on the LCD display when the feature is enabled. In random mode, it distorts your programmed ON/OFF time by +/- 0 to 30 minutes. For example, if you set the unit to turn on at 9PM and turn off at 10PM, it will turn on at a "random" time between 8:30PM to 9:30PM, and then turn off at a "random" time between 9:30PM and 10:30PM. I am not patient enough to figure out what the unit does with all the possible conflicts in programmed times and random mode, but the basic "random" mode does work on the 15154 model I got. Also, the newer model has Daylight Savings Time feature, as can be seen by CLOCK/DST button. To toggle DST, press and hold the CLOCK/DST button for 3 seconds. A tiny (+1h) indicator is visible on the LCD display when DST is enabled. I've uploaded an image to show the newer model.