Yes, the ProGrade Digital CFexpress Type A 120GB is compatible with the Sony FX3.
Sony FX3's highest-bitrate movie mode, XAVC S-I 4K (600Mbps), requires a CFexpress Type A memory card rated VPG200 or higher per Sony's own Help Guide. ProGrade Digital CFexpress Type A 120GB is VPG200-certified per ProGrade's own product page -- exactly meets the VPG200 floor. Type A slot confirmed on FX3.
“ProGrade Digital CFexpress 2.0 Type A Memory Card (Gold). Read 900MB/s | Write 800MB/s. Sustained write 450MB/s (VPG200 Rated).”
“This camera supports CFexpress Type A memory cards and SD memory cards (UHS-I, UHS-II compatible).”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)