“I'm confused about the difference between this (3543C) and the other Steripen (3060D). When I ordered, the description said that this one came with batteries, and the other didn't. But this one didn't come with batteries, and now the description also says that it doesn't come with batteries. Nor do I seem to understand what 'OPTI' in the title means. The package for this doesn't say OPTI on it anywhere; I thought that the OPTI meant that it had some sort of flashlight mode, which I can't seem to find. Can anyone clue me in?”
This pen has a longer battery life with regards to how many uses you have. The models we currently have do not come with batteries.|For more information you can read about the traveler at: http://www.steripen.com/traveler|and the traveler mini: http://www.steripen.com/traveler-mini
I believe OPTI means that it has the optical sensor, which is an improved model vs the old model with two metal pads. Only the Adventurer OPTI, and the Traveler Mini have this feature. It apparently makes the model work better in very clean and cold water with little minerals in it.
The 3543C has to Opti Sensor feature, an optical eye to sense the water (contrary to STP's customer service info). Older models use the conductivity measured between two SS pins to insure the device is in water...harmful UV out of water to user's eyes. The Opti is an incremental improvement to avoid false high conductivity readings in nearly pure water.