This is a 5V DC/DC regulator, specifically a Murata OKI-78SR-5/1.5-W36H-C!
They're highly efficient ~90%, and provide 5V @ 1.5A (7.5W) from a 7V to 36V input.
1.5A is ample for a Raspberry Pi Zero, but if using this with a Pi 3 or Pi 4 you'll need to keep a close eye on current consumption (and potentially take measures to reduce current usage).
It's deal if you need to produce 5V from a higher voltage power source for your project, and unlike noisy UBECs, this regulator provides < 75 mV peak-to-peak ripple.
- 7 - 36V Input
- 5V @ 1.5A Output (7.5W)
- < 75 mV peak-to-peak ripple
- Vertical mount, small footprint package
- “No heat sink” direct replacement for 3-terminal 78xx-series linear regulators
- High efficiency (~90%) with no external components
- Short circuit protection
- Outstanding thermal derating performance
- UL/EN/IEC 60950-1, 2nd Edition safety approvals