I suspect its anodized, as ive bought a few lian li bezels and pci slot covers which have all been black anodized, the finish is very similair to my old akasa eclipse 62, which i know for certain is anodized.
EDIT: Yep, it is anodized, found this on another site, cant link as theyre a competitor.
User Interface is very important key in Lian Li chassis. The external fixture, user interface, and the internal structure all has been test to meet Lian Li’s high quality standard. Lian Li launched the PC-A71F, with all aluminum alloy chassis, round edge design with stylish look. PC-A71F has hair-line brush anodized aluminum finishing with diamond cut detail.
The A71F is basically the same case but has a door front panel.