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Canonical battery record · checked 2 September 2026

SR421SW / 348

The SR421SW / 348 silver-oxide family is 4.8 × 2.15 mm. Preserve the W/SW drain designation unless current device or manufacturer guidance permits otherwise.

SR421SW348
Answer

SR421SW, 348 are the supported exact aliases for one 4.8 × 2.15 mm silver-oxide watch cell. No other family is treated as an automatic replacement.

Top profile · Ø 4.8 mm
Side profile · 2.15 mm high
Original proportional profiles. Scale is consistent within this diagram; screen size is not a physical ruler.
Format
Silver-oxide watch cell
Dimensions
4.8 × 2.15 mm
Voltage
1.55 V nominal
Chemistry
Silver oxide / zinc
Drain context
SW: low-drain profile
Rechargeable?
No — primary cell; do not recharge.
Capacity context
Manufacturer- and test-condition-specific; no universal capacity is asserted from the selection guide.
Confidence
High

Equivalence and confusion matrix

Code or familyClassificationReason
SR421SW · 348Exact equivalentThese evidence-backed markings resolve to this one canonical record and share its cited physical and electrical specification.
SR416SW / 337Not equivalentThe physical envelopes differ (4.8 × 2.15 mm versus 4.8 × 1.65 mm). Do not force, stack or infer equivalence from a shared diameter or code pattern.
SR521SW / 379Not equivalentThe physical envelopes differ (4.8 × 2.15 mm versus 5.8 × 2.15 mm). Do not force, stack or infer equivalence from a shared diameter or code pattern.
SR516SW / 317Not equivalentThe physical envelopes differ (4.8 × 2.15 mm versus 5.8 × 1.65 mm). Do not force, stack or infer equivalence from a shared diameter or code pattern.
SR527SW / 319Not equivalentThe physical envelopes differ (4.8 × 2.15 mm versus 5.8 × 2.7 mm). Do not force, stack or infer equivalence from a shared diameter or code pattern.

Supported application context

  • Watches specifying this exact code and drain class

Application context is limited to the scope stated in Murata Watch Battery Selection Guide; it is not a device compatibility claim.

This record belongs to the watch-cell system. Maker numbers are useful aliases, while the SW low-drain designation remains part of device selection.

SR421SW/348 is the taller of the two supported 4.8 mm watch cells. Its 2.15 mm height distinguishes it from 1.65 mm SR416SW even though both use the same SW low-drain classification.

What the code means

SR421SW identifies a silver-oxide watch cell. The W or SW suffix is part of the supported identity and records the manufacturer drain class.

Discharge and drain behaviour

Silver-oxide cells are selected for a comparatively stable working voltage. SW: low-drain profile remains material in watch applications, so a shared diameter and height do not erase the W/SW distinction.

Capacity context: Manufacturer- and test-condition-specific; no universal capacity is asserted from the selection guide.

Substitution guidance

Treat only the aliases on this page as exact equivalents. Another cell with the same dimensions is conditional at best unless its chemistry, nominal voltage and low-drain requirement also agree with the device specification.

Fact-level evidence

Murata Watch Battery Selection Guide

Published by Murata; page 1, SR421SW dimension and cross-reference row. Checked 2 September 2026. Independently presented facts only; publisher wording, layout and diagrams are not reproduced.

Corroborated against Maxell Button and Coin Battery Cross-reference Table; SR421SW row in the silver-oxide battery table.

Open primary source Open corroborating source
Not a device-fit guarantee.

Confirm the exact code, chemistry and drain requirement with the device maker. Keep button and coin cells away from children and never recharge this primary cell.