No, the Delkin Devices POWER CFexpress Type B 128GB is not compatible with the Sony A7 IV.
Sony A7 IV has a CFexpress Type A slot (Slot 1) and SD slot (Slot 2). CFexpress Type B uses a physically different, larger connector — it cannot be inserted into a Type A slot. Sony's memory card page explicitly states Type B cards cannot be used in this camera.
What works instead
See all compatible memory card for the Delkin Devices POWER CFexpress Type B 128GB →“CFexpress Type B memory cards cannot be used.”
Last verified:
Confidence: inferred