The STD120N4F6 is listed as obsolete. If you have this part on a BOM line, you are looking at a last-time-buy or surplus-channel procurement.
4 mOhm at 40 A — the switching spec that matters
That is a low on-resistance for a 40 V device in a DPAK, which keeps conduction losses down in a 80 A continuous-rated switch. The gate charge is 65 nC at 10 V, so the driver needs to source that charge for fast switching edges — budget the gate drive current against the switching frequency.
Automotive-grade construction
This is an AEC-Q101 qualified device from the DeepGATE and STripFET VI series, meaning it was characterised and released for automotive under-hood or chassis-domain switching applications. The DPAK (TO-252) footprint is a standard surface-mount power package, and the part is compatible with that footprint — the same pad layout used across many 40 V to 60 V N-channel MOSFETs in this class.