Just my opinion, take it for what it is. I have owned about 6-7 different micro brand gen bronze and brass watches over the past couple of years. The Z factory one's metal color does seem consistent with a CuSn8 bronze given it's red copper tones (CuSn8 is about 92% copper). The KW cases he posted across the boards showing 5 together that are being "slow tested with air and sweat", or something like that, all look more yellowish and more consistent with a brass color (brass is only about 50% copper) and doesn't have the same reddish tone as the Z factory version.