It really the luck of the draw. I have gotten these at ~$8.00 that were over 80 mW and some that were 50 mW. The diffraction grating are all the same for all of them. If you want a particular one, you will have to search for it. The ones I linked to have diffraction gratings included. The only difference between these and the $15.00 ones are maybe a tested power output, but without a laser power meter you'll never know.
