The Expansion fans are single-impeller units for adding radiator fans, filling case positions or matching the look of a build. They do not include an IO Controller, so each one must be daisy-chained to a single-frame main unit or connected to a separate controller. Each counts as one device toward the controller's six-device limit. They come in black and white only, with no Reverse version, and ship with a 100cm IO cable.

Figures are per fan, from the datasheet.

Their per-fan performance figures match the 420mm and 360mm regular frames exactly (140mm with 420mm, 120mm with 360mm), so mixing them in one build should give a consistent sound and airflow profile. They are the direct upgrade path from the regular Light Wings 120mm and 140mm fans, compared in the next section. Lighting is limited to two zones, impeller and frame.

The Black and White versions of each size have identical specifications, noise, airflow, pressure, EAN codes and price. All four use a 4-pole motor with a Fluid Dynamic Bearing, screw-only mounting (no push pins or washers), a 1000mm sleeved IO cable, zero RPM mode, a 60,000 hour lifespan at 25°C and a 5-year warranty. Electrically they are rated 12 V (6 to 13.2 V operating) with 0.30 A input current, 0.65 A safety current and 7.8 W input power. Approvals listed are CE, RoHS, UL, UKCA, WEEE and RCM.

The two sizes differ in a few places: the 120mm weighs 197 g and the 140mm 249.9 g, both including fixed cables; rated LED current is 0.84 A on the 120mm and 0.91 A on the 140mm; and retail packaging is 197 × 127 × 35.5 mm (0.25 kg) versus 217 × 147 × 35.5 mm (0.29 kg).

The single fans are not daisy-chain compatible, so keep that in mind.

Which size to choose

1. 420mm: the best fit for triple-140mm radiator or case positions when you want the most airflow and the most LEDs.
2. 360mm: the better pick for dense 360mm radiators where static pressure matters.
3. Reverse versions: choose these only when the blade-side look or reversed mounting matters, because the performance cost is real, especially at 360mm.
4. Expansion fans: add these to match a single-frame build or to fill positions a triple frame cannot, remembering the extra controller or daisy-chain requirement.

Light Wings Pro IO vs. regular Light Wings

Pro IO matches or beats the regular Light Wings on airflow, gives up some static pressure at 140mm, and is louder at full speed. It also changes almost everything around the fan: lighting, connection, control software, bearing and warranty. The regular fans are simpler and cheaper to wire into a standard motherboard, while Pro IO trades that simplicity for much deeper control.

The original Light Wings were be quiet!'s first ARGB fans, with ARGB lighting at the front and rear (18 LEDs on the 120mm, 20 on the 140mm), a rifle bearing and a 3-year warranty. The newer Light Wings LX moves 16 LEDs into the impeller hub, shining onto frosted blades, and adds a daisy-chainable ARGB cable and, on the high-speed models, a closed-loop motor. Each generation has four models on be quiet!'s Light Wings page: 120mm and 140mm, each as a PWM case fan and a PWM high-speed radiator fan. Black, white, Reverse and triple-pack versions also exist. The tables below compare them with the closest Pro IO Expansion fan at each size.

120mm

140mm

Where Pro IO lands. It sits in the high-speed tier of the regular lineup, not the quiet PWM tier.

1. 120mm: against the LX high-speed, airflow is almost identical (62.03 against 61.8 cfm) and pressure is about the same (2.47 against 2.51), but Pro IO runs 400 RPM faster and is 3 dB(A) louder at full speed. Against the original high-speed, which also spins at 2500 RPM, Pro IO moves about 19% more air at about 5% less pressure and is 2.9 dB(A) louder.
2. 140mm: Pro IO moves about 10% more air than the LX high-speed and about 16% more than the original high-speed, but with about 20% and 15% less static pressure, and is 2.3 and 1.8 dB(A) louder at full speed. On paper that makes it a stronger case-fan and open-radiator choice than a dense-radiator choice.
3. Quiet PWM models: the PWM-only regular fans are rated 20.6 to 25.5 dB(A) at full speed, far quieter than Pro IO, but move only 41.5 to 56 cfm.

What changes, in practice

1. Lighting: the original fans light a ring at the front and rear, and the LX lights the hub. Both use 16 to 20 LEDs and no lit frame. Pro IO adds a lit frame, 51 or 55 LEDs on the Expansion fans and 116 or 124 across four independent zones on the triple frames, plus calibration and temperature-reactive color.
2. Wiring: regular Light Wings use a 4-pin PWM header and a 5V 3-pin ARGB connector on a 500mm unsleeved cable, so your motherboard's RGB software can drive them, and the ARGB cable can be daisy-chained. Pro IO uses one proprietary cable (1000mm and sleeved on the Expansion fans) and an IO Controller (USB 2.0 and SATA power), which is tidier but ties you to be quiet!'s software.
3. Cooling control: regular fans follow the motherboard's fan curve and have no zero RPM mode. Pro IO adds semi-passive 0 RPM mode, per-fan and per-impeller curves, sensor-based groups, and a middle-impeller speed offset on the triple-fan frames.
4. Format: the triple-fan 420mm and 360mm Pro IO frames have no regular-Light-Wings equivalent. The regular range only comes in 120mm and 140mm, as single fans or as triple packs of three separate fans on an ARGB hub.
5. Build: Pro IO adds a continuous rubber frame for vibration damping and radiator sealing, a thicker 28mm frame (the regular fans are 25mm) and a Fluid Dynamic Bearing in place of the rifle bearing. The LX high-speed models add a closed-loop motor, which Pro IO also lists, and the LX 120mm PWM mentions a frame outlet that reduces air leaks.
6. Price and warranty: be quiet!'s listed price is €25.50 for the original 120mm PWM and €18.90 for the LX 120mm high-speed. Pro IO Expansion fans start at $54.90 / €42.90 (120mm) and $59.90 / €45.90 (140mm), more than double the LX 120mm high-speed, and the triple frames start at $132.90 / €109.90. Warranty rises from 3 to 5 years.

Who should choose which. Choose regular Light Wings or Light Wings LX if you want standard motherboard control, lower cost and RGB software you already use. Choose Light Wings Pro IO if you want the single-cable look, a lit frame, deep fan-curve control and a longer warranty, and you accept the controller and software dependence.