I have one. They quote 5nm accuracy but mine is neaerr to 1nm. The pro model comes with an interchangeabl;e slit plate allowing smaller slits to be used. Yes, it uses Theremino software which uses 2-point calibration. That seems to give very accurate measurements for my laser pointers, form deeep blue to red, and my IR laser and my TV remove around (I thnink I recall) at 890nm. I can read the sodium spectrum from distant street lights nd I've found invisible security cameras from their IR flood lights (just for fun). It can do absorption too, though I have not tried it. It is sensitive from 400 nm (quoted - mines goes down to 360 nm) up to 1000 nm. Now - it doesn't do absolute intensity, and the webcam driver means you have to know how to get the best from it. It is a compromise between cost and functionality. It won't do everything anyone might ask of a spectrometer but then it's less than 1% of the cost of a typical Ocvean Optics spec and does many of the same things just as well. It suits many people like me, who want to do things like testing power LEDs and other growing lights. See the videos and the reviews. It's not a high-end instrument - DUHHH - but neither it is a toy, though at this price you could certainly buy one for your kids to play with.