Opposite seat jobs. Same shopping aisle.
The Sihoo Doro C300 is full mesh seat and back, self-adaptive lumbar (per Sihoo), adjustable headrest, and 4D arms that Sihoo says follow the recline. $279.99−50%.
The COLAMY Atlas is a 3.5" foam seat with a mesh back, manual lumbar, a published sliding seat pan, and four lockable recline angles. price varies.
Short fork:
- Warm room / hate foam heat / want lumbar that moves without a dial → C300.
- Prefer a cushion, need documented seat-depth travel, want manual lumbar and lock angles → Atlas.
- Foam seat this site has used vs C300 → /compare/uplift-clarksville-vs-sihoo-c300.
- Step-up Sihoo → /reviews/sihoo-doro-c300-pro-v2-review.
This page is standard black C300 (no footrest) vs current dark-gray Atlas. Pro / V2 / footrest / Atlas-01 variants are other products.
Specs from current manufacturer pages. Feature forks, not borrowed comfort scores.
Specs that matter
| Sihoo C300 | COLAMY Atlas | |
|---|---|---|
| Price | $279.99−50% | price varies |
| Seat | Full mesh | 3.5" high-density foam (COLAMY) |
| Back | Mesh | Mesh |
| Lumbar | Self-adaptive (Sihoo) | Manual adjust (range not listed) |
| Seat depth | 17.13-18.11 in published; confirm slider with Sihoo if you need one | 15.8-17.8 in sliding (2 in travel) |
| Arms | 4D; Sihoo says coordinated with recline | 4D listed |
| Headrest | Height, depth, rotation | 3 in height + 30° rotation |
| Recline | Weight-sensing, up to 130° | Locks at 107° / 115° / 123° / 132° |
| Capacity | 330 lb | 300 lb |
| Warranty | 3 years | 3 years |
Measure your current chair's sit height and depth before trusting either column.
Seat material is the real fork
C300: air through seat and back. The warmer-office material pick. Mesh tension and edge feel still depend on your body.
Atlas: foam cushion + mesh back. Pick it if you already know you want padding, not a suspended mesh pan. COLAMY's "high-density memory foam" label is theirs, not a firmness score from here.
Lumbar: automatic or manual
C300: self-adaptive, fewer dials. Great if you hate fiddling; annoying if you want one exact pressure point.
Atlas: manual lumbar listed, no numeric travel published. Choose Atlas when the presence of a control matters, not because the sheet proves a better curve.
Atlas: seat-depth control
Published 15.8-17.8 in slide, 20 in width, 16.7-21 in height. Depth control lets you keep your back on the backrest without the front edge eating your calves. Also: 4D arms, headrest, four lock angles, 300 lb, 3-year warranty.
C300: full-mesh package
Mesh seat/back, headrest, self-adaptive lumbar, coordinated 4D arms, weight-sensing recline to 130°, 330 lb, ~50.93 lb chair, 3-year warranty. Treat the published depth range as geometry unless Sihoo confirms a user slider on the exact standard model.
Arms, headrest, recline
Both say 4D, not the same directions or pad stability. C300 has the clearer paper story for arms that follow a lean. Headrests both adjust; Sihoo lists height/depth/rotation, COLAMY lists 3 in height + 30° rotate.
Want repeatable lock stops → Atlas. Prefer weight-responsive lean with fewer lumbar dials → C300.
Get the C300 if
- You want mesh on seat and back
- Self-adaptive lumbar (Sihoo's description) fits how you sit
- Coordinated armrests during recline matter
- You need the 330 lb rating
- You can live without a clearly documented seat slider
Get the Atlas if
- You want foam seat + mesh back
- You need the published 16.7-21 in seat-height range
- You want the documented 2 in seat-depth adjust
- You prefer manual lumbar
- Four lock angles beat a weight-sensing recline for your workflow
Fit tips
- Measure your current seat height, usable depth, and arm height first.
- Set depth so the front edge clears your calves while your back stays planted.
- Pick seat material before feature-count bragging.
- Watch Pro / V2 / footrest name twins.
- Use the return window as the real fit test.
Frequently asked questions
Which is "better"?
C300 for full mesh, self-adaptive lumbar, coordinated arms. Atlas for foam, sliding depth, manual lumbar. No universal comfort winner from a sheet.
Warm office?
C300 is the more logical material pick (mesh seat + back). Atlas mesh back still sits on foam.
Atlas seat depth?
Yes. 15.8-17.8 in (2 in travel), plus 20 in width and 16.7-21 in height on the current page.
C300 seat depth adjustable?
Sihoo publishes 17.13-18.11 in depth; confirm a user slider with Sihoo if depth adjust is mandatory.
Better lumbar?
Control style preference only until you sit. Self-adaptive vs manual. Verify in the return window.
Longer warranty?
Both list 3 years. Read exclusions and claim paths. Headlines can match while policies differ.
Also: /guides/best-ergonomic-chairs-under-400 · /guides/best-ergonomic-chairs-under-600.
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