Apple Watch Series 4 “40 mm” Aluminum GPS Specs

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Apple Watch Series 4 – MU642LL/A – Watch4,1 – A1977

Apple Watch Series 4 40 mm Cellular(US-CA) Specs

About This Watch

The Apple Watch Series 4 is very similar to previous devices in its line-up but features larger screens as well as a few upgraded components which improve the functionality and features of the watch. The Series 4 has larger screen sizes of 40 mm and 44 mm which allows for more internal space inside the watch and more screen area for apps to use. This particular model does not feature cellular capabilities but higher end models do.

Apple decided to focus on health with this device. This was emphasised by the new accelerometer and gyroscope which are used to detect when a user has a fall. The heart rate monitor already tracks sudden spikes or irregular patterns and warns users of the risk of a stroke. Apple introduced an electrical heart sensor(ECG) into the Series 4 watch. This single pulse electrical heart sensor is able to detect signs of atrial fibrillation and alter the user.

Apple S4

1 GB

16 GB Flash Storage

18 Hours

Storage & Memory

The Apple Watch Series 4 comes with 1 GB of RAM and 8 GB of memory.

Screen Size and Resolution

This Apple Watch Series 4 has a 40 mm sized OLED display with strengthened Ion-X glass and a resolution of 324×394. This display is force touch capable and also has a water resistance protection of an estimated 50 meters.

OS & Processor

The Apple Watch Series 4 comes with Apple watchOS 5 for its operating system. It is also powered by a dual-core Apple S4 processor. Apple has not released processing speeds for this processor.

Battery

The Apple Watch Series 4 battery is expected to go for up to 18 hours overall but specifically 2 hours of talk time, 10 hours of audio and up to 6 hours of working out while using GPS. There is no substantial improvement from the Apple Watch 3 on battery life.

Inclusive Features

The Apple Watch includes the following features:

Force touch OLED display.
Digital crown control piece.
Multiple wristband units.
Heart-rate monitor.
Electrical heart sensor (ECG).
Emergency heart-rate detection.
Wireless Charging.
Bluetooth.
Water resistant.
GPS tracker.

Introduction Date: September 12, 2018					Discontinued Date: September 10, 2019
Processors					Memory
Processors		1 (2 cores)			Onboard RAM	1 GB
Processor Speed		Pending			Storage
Processor Type		Apple S4			Capacity	8 GB
Connectivity Details					Song Capacity	N/A
USB Support				N/A	Photo Capacity	N/A
FireWire Support				N/A	Description
Standard Wireless				802.11b/g/n 2.4 GHz	Case Type		Watch
Standard Bluetooth				5.0	Form Factor		Apple Watch Series 4 (40 mm)
Cell Network				N/A	Housing Color		Aluminum/Steel
Battery Details					Controller		Digital Crown
Battery Type	Lithium Ion				Apple Order Number		MU642LL/A
Battery Life	2 – 18 hours				Apple Subfamily		Watch Series 4 40mm
Standby Time	N/A				Apple Model Number		A1977 (EMC 3225)
Operating System and Display					Model ID		Watch4,1
Pre-installed OS			watchOS 5.0 (16R364)		Camera		None
Maximum OS			Current OS		Dimensions		40mmx34mmx10.7mm
Built-in Display			1.8 OLED		Average Weight		1.06/1.40 oz. (30.1g/39.8)
Display Resolution			324×394		Minimum iPhone Support		iPhone 5

Identifier reference: MU642LL/A, A1977, EMC 3225. Use these together because one Apple identifier can sometimes cover multiple configurations.

Last reviewed by Techable: August 14, 2024Identifiers checked: order number, A-number, EMC, and model identifier when available.

Model summary

This Apple Watch at a glance

Family: Apple Watch
Order Number: MU642LL/A
Model Number: A1977
EMC: 3225
Year: 2019

Use the order number, A-number, EMC, and model identifier together when comparing, buying, or selling this device.

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Search by A-number, EMC, order number, or model identifier.

Next steps

Use the spec table to confirm the exact device, then choose the right lookup, buy, or sell path.

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Common questions

Is MU642LL/A the same as A1977?

Not exactly. MU642LL/A usually points to a specific retail configuration, while A1977 identifies the broader Apple hardware family. Always check the EMC and model identifier too.

What Apple Watch is model A1977?

A1977 is the Apple A-number shown for this Apple Watch family. Use the order number, EMC, and model identifier on this page to narrow the exact configuration.

What does EMC 3225 mean?

The EMC number is another Apple hardware identifier. It helps separate closely related models that may share a similar name, year, or A-number.

Can the RAM or SSD be upgraded?

Check the spec table for the exact configuration. Many newer Apple Silicon Macs have memory and storage integrated into the board, so RAM and SSD upgrades are often not practical after purchase.

What macOS versions work with this model?

Use the model identifier, release year, and processor family from the spec table when checking macOS compatibility. Compatibility can change as Apple releases new macOS versions.

Is this Apple Watch still worth buying used?

It can be, depending on price, battery health, memory, storage, and condition. Compare this exact order number and model identifier against similar Techable listings before buying.

How much is this Apple Watch worth?

Value depends on RAM, storage, battery health, cosmetic condition, accessories, and market demand. Use the SellMac path on this page for a quote or use the identifiers here when comparing resale prices.

What should I search if this page is not the exact configuration?

Search the order number first when available, then compare the A-number, EMC, model identifier, year, chip, RAM, and storage. The same A-number can cover more than one configuration.

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