Most home office buyers settle on the Ergotron LX as their first monitor arm. It’s affordable and covers the widest load band of the three arms here. Buyers outfitting a high-end home office often look past it to two premium alternatives: the Herman Miller Flo Plus and the Humanscale M2.1. Where this page links the Flo on Amazon it points to the single-arm Herman Miller Flo (Amazon Associates), the listing that carries a stable ASIN; the Plus is the higher-capacity variant of the same design.
This comparison uses the manufacturers’ published specifications: capacity, reach, lift, VESA support, and warranty. It makes no claims about how the arms feel in use, because this site does not test hardware. The headline from the spec sheets is that the three arms are not interchangeable on load: Humanscale rates the M2.1 for far lighter panels than the LX.
TL;DR Verdict
| Rank | Arm | Best for | Price |
|---|---|---|---|
| 1 (value) | Ergotron LX (Amazon Associates) | The default for single panels from 7 to 25 lbs | ~$170 |
| 2 (premium, mid-weight) | Herman Miller Flo Plus | Design-led offices with a panel inside its 6 to 22 lb range | ~$370 |
| 3 (premium, light panels) | Humanscale M2.1 | Light flat panels of 5 to 15.5 lbs; longest reach and warranty | ~$420 |
How the Three Compare on Paper
Across all three arms:
- Spring counterbalance rather than thumb-screw joints (Ergotron calls its version Constant Force)
- Published reach between 24 and 27 inches
- Warranties from 10 to 15 years
- Standard 100×100 VESA support
Where they differ most is load. The LX is rated 7 to 25 lbs and the Flo Plus 6 to 22 lbs. Humanscale’s weight capacity chart rates the M2.1 at 5 to 15.5 lbs (2.3 to 7 kg) for flat screens and 5 to 12.5 lbs for curved ones. A 16 to 25 lb monitor that fits the LX is outside the M2.1’s range altogether, so check your panel’s stand-free weight before shortlisting on price or looks.
What the premium tier adds, on the published specs:
- Warranty: 12 years on the Flo Plus and 15 on the M2.1, against 10 on the LX.
- Materials: die-cast aluminum on the Flo Plus and forged aluminum on the M2.1, against the LX’s aluminum and powder-coated cast metal.
- VESA range: the Flo Plus adds a 200×100 option that neither of the other two lists.
Cable routing also differs by design. If a clean cable run matters, check each manufacturer’s installation guide for how the cables pass through the arm before buying.
Ergotron LX: The Sensible Pick
The LX is the benchmark arm in this price band. Replacement parts are sold individually, and it carries a 10-year warranty.
Spec sheet:
- Capacity: 7–25 lbs
- Reach: 25”
- Vertical travel: 13”
- Tilt: 70°/5°
- Pan: 360°
- VESA: 75×75, 100×100
- Warranty: 10 years
- Build: aluminum + cast metal, powder-coated
On paper: the widest load band of the three and the lowest price. Ergotron notes that above 20 lbs up to 4.5 inches of low travel may be lost, which matters if the screen has to sit low; the Ergotron LX review covers that restriction.
What you give up vs Flo Plus / M2.1:
- A shorter warranty (10 years against 12 and 15)
- A more industrial look, if appearance is a priority
Buy: Ergotron LX on Amazon (Amazon Associates). Available in matte black, polished aluminum, and white, all $170 or close.
Herman Miller Flo Plus: The Aesthetic Pick
The Flo Plus is the arm Herman Miller sells alongside its premium chairs and desks. It’s designed to match the visual language of the Aeron / Embody chair lines.
Spec sheet:
- Capacity: 6–22 lbs
- Reach: 24”
- Vertical travel: 12”
- Tilt: 75°/5°
- Pan: 360°
- VESA: 75×75, 100×100, 200×100
- Warranty: 12 years
- Build: die-cast aluminum, polished or matte finish
On paper: the Flo Plus sits between the other two on load, with a 22 lb ceiling, and is the only one of the three to list a 200×100 pattern. Keep the variants apart when shopping: Herman Miller’s Flo product sheet rates the standard Flo at 4.4 to 15.4 lbs, so a listing that just says “Flo” may describe the lighter arm.
What you give up vs LX:
- 2x the price
- Less universally available (sold through Herman Miller dealer network and direct)
- A 22 lb ceiling against the LX’s 25
What you give up vs M2.1:
- Three fewer warranty years (12 against 15) and 3 inches less reach
Buy: Herman Miller Flo Plus direct.
Humanscale M2.1: The Light-Panel Premium Pick
The M2.1 is Humanscale’s lighter-duty arm. Humanscale’s M/Class upgrade notes now pair it with the M2 Pro, rated 5 to 22 lbs, and move its heavier M8.1 and M10 arms over to the M8 Pro, which the heavy-monitor arm picks cover.
Spec sheet:
- Capacity: 5–15.5 lbs flat (2.3–7 kg); 5–12.5 lbs curved
- Reach: 27”
- Vertical travel: 13”
- Tilt: 75°/5°
- Pan: 360°
- VESA: 75×75, 100×100
- Warranty: 15 years
- Build: forged aluminum, multiple finishes
On paper: the longest reach and longest warranty of the three, but the lowest ceiling by a wide margin. A typical 27-inch panel, which our monitor weight by size figures put at 9 to 12 lbs without its stand, fits. A 34-inch ultrawide near 17 lbs does not. If your panel is over 15.5 lbs flat, look at the M2 Pro or the LX instead.
What you give up vs LX:
- 2.5x the price
- 9.5 lbs of capacity: a 15.5 lb flat-panel ceiling against the LX’s 25
What you give up vs Flo Plus:
- A lower ceiling (15.5 lbs flat against 22) and no 200×100 option
- Higher price
Buy: Humanscale M2.1 direct.
Long-Term Holding and Drift
None of the three manufacturers publishes a drift figure, and this site has not measured one, so there is no basis for ranking these arms on long-term sag. The published commitment that does exist is the warranty: 10 years on the LX, 12 on the Flo Plus, 15 on the M2.1.
What the specs do show is that drift depends on where your panel sits in each arm’s range. A panel below an arm’s minimum floats upward, one above its maximum sinks, and the LX’s low-travel restriction applies above 20 lbs. Size each arm so your stand-free panel weight sits inside its band, and re-tension whenever the load changes, as covered in monitor arm drifting or sagging.
Who Should Buy Which
- You want the best value, or your panel is over 15.5 lbs: LX. The widest load band and the lowest price.
- You’re outfitting a design-forward home office with a panel up to 22 lbs: Flo Plus.
- You have a light flat panel of 5 to 15.5 lbs and want the longest reach and warranty: M2.1, or the M2 Pro for a heavier panel up to 22 lbs.
- You have a heavy ultrawide: None of these. Look at the Ergotron HX (Amazon Associates) or the heavy-monitor arm picks, which include the Humanscale M8 Pro.
What About the Herman Miller Jarvis?
The Jarvis Monitor Arm, the former Fully Jarvis and now sold under Herman Miller after Fully wound down, lists at $175, close to the LX, and is often cross-shopped. It’s a competent arm: 20 lb capacity, VESA 75×75 and 100×100, and a 10-year warranty that matches the LX’s. The LX is still the better pick for most buyers because:
- Wider replacement-parts availability (the LX has been in production longer)
- A 25 lb ceiling against the Jarvis’s 20 lbs, which matters on 27” and 32” panels
If aesthetics drive your decision and you want a wider color range and a cleaner cable channel, the Jarvis is fine. If you want the best value, LX.
Related Reading
- Ergotron LX vs HX vs MX: Ergotron internal lineup
- VESA compatibility explained: for mount pattern questions
- How to choose a monitor arm: full buyer’s guide
- Dual monitor setup guide: for two-monitor configurations
- Sister site StandDeskReview
Final Word
For most home office users, the Ergotron LX is the right pick: the widest published load band of the three at the lowest price. The Flo Plus and M2.1 add longer warranties and premium materials at roughly 2 to 2.5 times the LX’s price, and the M2.1 only suits light panels up to 15.5 lbs. Spend the extra money only if those things are real priorities for you, not as a default. Whichever tier you land on, the arm has to contain your panel’s weight at both ends of its range: check the figures in monitor weight by size and confirm the match with the Monitor Arm Fit Checker.
