I've seen some blue laser pointers that claim 445nm, others claim 447nm, while others 450nm. Are these all actually refering to the same technology of laser diode, but the sellers are being imprecise and just rounding the numbers differently? 447 rounded to the nearest 5 would be 445, while 447 rounded to the nearest 10 would be 450. Are all of these laser pointers (regardless of what the company is advertizing them as) actually using a 447nm laser diode? Or are these actually 3 different wavelengths of laser diodes?