The Stax UA7-CF has surprisingly high effective mass for a carbon fiber type. It is sixteen grams, which enables it to be used with many of the heavier modern moving coils. As I understand it, the CF model was produced only in response to complaints that some setups revealed a bit of unwanted resonance in the standard aluminum wand UA-7, so both models have essentially the same mass. I own two of the standard UA-7 tonearms, and have not heard the resonance issue, but maybe that is due to my particular setup. I have no doubt that the carbon fiber model is its sonic superior, however. The Stax tonearm of either configuration is extremely well-made with jeweled bearings and first-class construction. It is a keeper, even if you own one of today's better tonearms.