SR521SW is a common watch/button cell size with several cross-reference codes. You’ll often see these used interchangeably for the same size:

• 379, 521, SR521, SR521SW
• D379, V379, CX521, 618
• AG0, LR521, LR63 (alkaline alternatives)

Helpful tips:

• “SR” indicates silver oxide; “LR/AG” indicates alkaline. Chemistries can perform differently.
• “SW” typically denotes a low‑drain watch type; some devices call for “W” (high‑drain).
• Match the code on your device or manual. Compatibility can vary by device.
• On Walmart.com, search by the code (e.g., 379 or SR521SW) and choose the pack size that suits your needs.

In many listings, 379 is the industry code that corresponds to the SR521SW watch battery size. It’s commonly used as a low‑drain, silver oxide option for devices that specify SR521SW.

• Check the suffix: If your device calls for “SW,” look for a low‑drain version; “W” typically signals high‑drain.
• Match chemistry: Silver oxide (SR) vs. alkaline (LR/AG) can affect run time and voltage stability.
• Confirm fit: Always verify the code printed in your device or manual.
• Shopping tip: Use Walmart.com filters to find this size across single and multi‑packs and compare features in the descriptions.

AG0/LR521 is an alkaline version of the same physical size as SR521SW. It may work in some devices, but performance characteristics can differ from silver oxide.

• Chemistry matters: Silver oxide (SR) typically offers steadier voltage and may last longer in low‑drain devices than alkaline (AG/LR).
• Device needs vary: Watches or electronics that prefer stable voltage often specify SR types. Check your manual for guidance.
• Avoid mixing: Don’t mix alkaline and silver oxide cells in the same device.
• Result may vary: If you choose AG0, monitor performance and replace as needed. On Walmart.com, you can compare both chemistries under the same size code.

Installing a button cell is a quick task, but care helps:

1. Power off the device and work on a clean, well-lit surface.
2. Open carefully, using the proper tool for your watch or gadget.
3. Note polarity before removing the old cell (+ side orientation).
4. Avoid touching battery faces with bare fingers; use clean, dry hands or plastic tweezers.
5. Insert the new SR521SW in the same orientation and ensure it’s seated flat.
6. Close and test the device gently, without over-tightening.
7. Dispose or recycle used batteries per local guidelines.

Keep small batteries away from children and pets, and don’t heat, puncture, or attempt to recharge non‑rechargeable cells.

Good storage can help maintain performance over time:

• Keep in original packaging to prevent short-circuiting and mix-ups.
• Store cool, dry, and indoors, away from heat, humidity, and direct sunlight.
• Avoid metal contact; don’t carry loose cells in pockets or bags.
• Rotate your stock and use older packs first; check date codes if provided.
• Don’t mix types (alkaline and silver oxide) in the same container for active use.
• Safety first: Keep out of reach of children and pets.
• End-of-life: Follow local recycling or disposal guidance. You can also review Walmart’s returns and policies online for unopened items, subject to current terms.