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A4Tech FB45CS Air specifications and in-depth review

A4Tech FB45CS Air

Manufacturer: A4Tech

The A4Tech FB45CS Air is a right-handed mouse designed for both productivity and gaming use, offering a versatile triple-connection setup across 2.4GHz wireless, Bluetooth, and USB. Weighing in at 81g and measuring 108mm in length, it strikes a fairly compact and lightweight profile. One of its more notable characteristics is its removable battery, which sidesteps the need for built-in recharging and supports an exceptionally long rated battery life of 5840 hours. The mouse also supports gesture input, adding a layer of navigational flexibility beyond standard button use.

On the performance side, the A4Tech FB45CS Air uses an optical sensor with a fixed range between 1000 and 2000 DPI, though DPI is not adjustable on the fly as there is no dedicated DPI switching button. All 7 buttons are programmable, including 2 side buttons, but there is no onboard memory for storing profiles, and no profile switching button is present. The scroll wheel does not tilt, and the design omits RGB lighting and extra weights. A 1.5m cable is included for wired use, and the mouse can be operated while charging, providing uninterrupted use when needed.

Pros
  • Triple connectivity via 2.4GHz wireless, Bluetooth 5, and USB offers flexible setup options across different devices
  • Rated battery life of 5840 hours provides exceptionally long use between battery replacements
  • All 7 buttons are programmable, giving users full control over the entire button layout
  • The removable battery design means power can be restored instantly by swapping in a fresh battery
  • Gesture support adds an extra layer of navigational input beyond the standard button configuration
  • At 81g and with compact dimensions, the mouse remains light and easy to handle during extended use
Cons
  • DPI is not adjustable, limiting sensitivity customization for users who need to switch between different tasks or surfaces
  • The maximum DPI of 2000 is relatively modest, which may not satisfy users who require finer tracking precision
  • No dedicated DPI or profile switching buttons means on-the-fly adjustments cannot be made directly on the mouse
  • No onboard memory profiles are available, so custom button configurations cannot be stored on the device itself
  • The design is right-handed only, making it unsuitable for left-handed users
  • There is no tilting or thumb scroll wheel, restricting horizontal scrolling options
Who is this for?

The A4Tech FB45CS Air is a good match for users who regularly switch between multiple devices, as its triple connectivity options — 2.4GHz wireless, Bluetooth 5, and USB — allow seamless transitions across setups without extra hardware. The 5840-hour battery life combined with a removable battery makes it particularly well-suited for users who prefer low-maintenance peripherals and want to avoid frequent charging interruptions. Its lightweight 81g build and compact dimensions also make it a practical choice for those who use a mouse across different locations and need something easy to carry and set up quickly.

Who is this NOT for?

Users who rely on adjustable DPI for fast sensitivity switching — such as those who alternate between detailed design work and fast-paced gaming — will find the fixed sensor range limiting, especially without a dedicated DPI switching button. The mouse is shaped exclusively for right-handed users, making it entirely unsuitable for anyone who uses their left hand. Additionally, those who value a highly customizable hardware experience, including onboard profile storage or precise sensitivity tuning, will find the lack of onboard memory and profile switching a meaningful shortcoming in more demanding or varied workflow scenarios.

Performance:

polling rate 125 Hz
maximum DPI 2000 DPI
minimum DPI 1000 DPI
has adjustable DPI ✕

The A4Tech FB45CS Air operates at a polling rate of 125 Hz and uses an optical sensor with a fixed sensitivity range spanning from 1000 to 2000 DPI. DPI is not adjustable on the fly, as the mouse does not include an adjustable DPI feature, meaning the sensor works at a set level within that range without user-controlled switching.

General info:

Type Productivity, Gaming
connection type 2.4GHz wireless, Bluetooth, USB
sensor Optical Sensor
onboard memory profiles 0
Bluetooth version 5
has gesture support ✓
Battery life 5840 hours
can use while charging ✓
has a rechargeable battery ✕
has a removable battery ✓

The A4Tech FB45CS Air is a productivity and gaming mouse that connects via 2.4GHz wireless, Bluetooth 5, and USB, giving users flexible options depending on their setup. It uses an optical sensor and supports gesture input for expanded navigation control. The mouse runs on a removable battery with a rated battery life of 5840 hours, and while it does not have a built-in rechargeable battery, it can still be used while charging. There are no onboard memory profiles available for storing custom configurations.

Buttons:

number of buttons 7
number of side buttons 2
number of programmable buttons 7
has a DPI switching button ✕
has a profile switching button ✕

The A4Tech FB45CS Air features 7 buttons in total, all of which are programmable, allowing users to assign custom functions across the entire button layout. This includes 2 side buttons positioned for thumb access. However, the mouse does not include a dedicated DPI switching button or a profile switching button, so sensitivity adjustments and profile changes cannot be made directly on the device.

Design:

Orientation Right-handed
weight 81 g
has RGB lighting ✕
has a tilting scroll wheel ✕
has a thumb scroll wheel ✕
has extra weights ✕
cable length 1.5 m
volume 317.52 cm³
thickness 42 mm
height 108 mm
width 70 mm

The A4Tech FB45CS Air is designed exclusively for right-handed use and has a compact footprint of 108mm in height, 70mm in width, and 42mm in thickness, with a total volume of 317.52 cm³. It weighs 81g, keeping the overall feel light during extended sessions. A 1.5m cable is included for wired connection. The mouse does not feature RGB lighting, a tilting scroll wheel, a thumb scroll wheel, or adjustable extra weights, keeping the design straightforward and free of additional embellishments.

Final Verdict

The A4Tech FB45CS Air is a pragmatic, connectivity-focused mouse that covers the essentials for both productivity and general gaming use without overcomplicating its feature set. Its standout quality is undoubtedly the triple-connection flexibility combined with an extraordinary battery life of 5840 hours, making it a dependable choice for users who move between devices or simply want a mouse that rarely demands attention. The fully programmable button layout and gesture support add functional depth, though users with more specialized demands — particularly around sensitivity tuning or left-handed ergonomics — will find the hardware lacking in those areas. For right-handed users seeking a lightweight, low-maintenance wireless mouse with broad connectivity, the FB45CS Air delivers a focused and reliable experience.

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