The Ztl file, composed of multiple subtools, see the color block diagram for the specific composition. this is a high-model the poly amount has been moderately optimized by the Decimation master of zbrush, and there is no subdivision level. Output obj format, because the poly amount is too high, the poly amount are further reduced before output, and the poly acount of obj is 1409868. The rendering image is by Zbrush's own renderer , and the file retains the materials and lights used. You can get more information from the preview pic.If any question please write to me.