Storage and Accessories · Head to head
Same family, same ten-year warranty, and one published sentence that decides the whole comparison if your monitors are heavy.
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Side by side
Buy two of these if
Your screens are over 20 lb or you want them positioned independently.
Full write-up below#ad · Price shown on Amazon · Affiliate disclosure for the link to LX Desk Monitor Arm
Buy this if
Your screens are light, and one clamp point on a thin top is worth more than travel.
Full write-up below#ad · Price shown on Amazon · Affiliate disclosure for the link to LX Dual Side-by-Side Arm
| LX (single) | LX Dual Side-by-Side | |
|---|---|---|
| Capacity | 26 lb (11.8 kg) | 7 to 25 lb (3.2 to 11.3 kg) per LX arm |
| Lift range | 33 cm (about 13") | Up to 4.5" less with monitors over 20 lb — 8.5" total |
| Clamp points | One per arm | One for both screens |
| Screen arrangement | Fully independent | Side by side |
| Warranty | 10 years | 10 years |
Ergotron's own published caveat
It is worth noting how unusual that disclosure is. Most arm makers publish a maximum capacity and a maximum travel and let you assume you get both at once. Ergotron tells you the trade, which is a reason to trust the rest of its figures.
The practical consequence for a sit-stand user: 8.5" of travel may not be enough to keep your screens at eye level across both a seated and a standing desk position. The entire reason to buy an arm for a sit-stand desk is that decoupling, so losing it defeats the purchase.
The dual arm's real advantage is that it puts one clamp on your desk instead of two.
Buy two single LX arms if your monitors are over 20 lb each, you want one screen portrait, you sit off-center, or you want the full 13" of travel on both. It costs more and it is the better setup.
Buy the LX Dual if your monitors are light, they live side by side, and a single clamp point on a thin sit-stand desktop is worth more to you than the extra travel.
Buy one single LX if you run one screen and a laptop. Most people overbuy here.
In detail
Your screens are over 20 lb or you want them positioned independently.
Skip it if your desktop is under about 0.6" thick or has no clear clamp edge — you will be fighting the mount, not the arm.
#ad · Price shown on Amazon · Affiliate disclosure for the link to LX Desk Monitor Arm
Your screens are light, and one clamp point on a thin top is worth more than travel.
Skip it if your monitors are over 20 lb each and you need full vertical travel — Ergotron's own figures say you will not get it. Two single arms are the better answer.
#ad · Price shown on Amazon · Affiliate disclosure for the link to LX Dual Side-by-Side Arm
How we picked
Plenty of sites imply a lab. We don't have one, and we say so. One desk here is genuinely owner-tested — the UPLIFT V2 that Mike bought and works at daily. Everything else is chosen the way an informed buyer would choose it: read the maker's spec sheet, manual and warranty terms; record the figures that decide whether a desk fits a body and stays still at height; check whether replacement parts are actually sold; then score each pick against a published rubric.
Scores are editorial judgments from that documented research, not lab results, and every product is labeled owner-tested or researched so you can weigh it accordingly. Nobody pays for placement. The rubric and the weights are on the How We Pick page.
Questions
Usually 4 to 8 lb less than the figure you find first, because most published weights include the stand. The manufacturer's spec sheet normally lists both — the arm only carries the panel.
Physically yes, if your desk edge has room. Practically it is rarely worth it — three screens on two mounting systems is harder to align than three screens on three arms.
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Receipts
Specs come from the maker's own spec pages and manuals; health claims from named medical institutions and published research; tax mechanics from IRS material. Where a figure isn't published, we say so rather than estimating it. Read the full method.