They replaced the sensor in it to one that is filtered to make its spectral sensitivity more closely match the color sensitivity of film. They also claimed to have reduced the amount of flare in the optical system. I have one of these, and a regular un-modified Pentax Digital Spotmeter. I did some extensive testing a couple years ago and found that the biggest difference is in sensitivity to infrared. The modified meter is, like film, completely insensitive to IR. That makes metering things that reflect a lot of IR, like green foliage, much more accurate and it improves accuracy in scene lit by incandescent lights, which produce a lot of IR. Aside from that, it is a little more sensitive to blue and less sensitive to red than the normal meter, which is how most B&W films are.