For anyone moving up from an ordinary office chair to an ergonomic one, SIHOO's M series is a popular place to start: around 5,000–7,000 baht for the core features of an ergonomic chair. The questions we hear most are "how is the M18 different from the M57?" and "which M59 should I get?" This guide answers both in one place.
Specifications come from the SIHOO Thailand product pages. Prices are the website prices as of November 2026 and may change with promotions.
The three chairs in one paragraph each
- SIHOO M18: mesh backrest, but an 8 cm memory-foam W-shaped seat that feels soft. Good if you do not like mesh seats.
- SIHOO M57: full mesh, 3D armrests, 2D lumbar support and a plated steel base. The sturdiest of the group.
- The M59 family: several variants. The main ones are the M59AS (Auto Adaptive lumbar pillow, flip-back armrests) and the Smart M59 / M59Pro (spring lumbar support, flip-up 3D armrests, reclines to 136°).
Specifications side by side
| Feature | M18 | M57 | M59AS | Smart M59Pro |
|---|---|---|---|---|
| Website price (Nov 2026) | ฿4,990 (with footrest ฿5,500) | ฿6,590 | ฿4,990 | ฿5,990 (M59Pro-FT ฿6,490 / Smart M59 ฿4,990) |
| Seat | 8 cm memory foam, W-shaped | Mesh, waterfall edge | Mesh | Mesh |
| Backrest | Mesh | Mesh, dual frame | Mesh, dual frame, high back | Mesh, PA-and-fibre frame |
| Lumbar support | Adjustable | 2D (5 cm height, 4 cm depth) | Auto Adaptive | Spring, adapts to your back |
| Headrest | 2D | 2D (8 cm height, 45° rotation) | 3D (11 cm height, 45° rotation) | Two-joint, 8 height positions + angle |
| Armrests | Adjustable | 3D | 2D, flip back, 90° rotation | 3D, flip up |
| Recline | 109° / 118° / 128° | 109° / 116° / 126° | 115°–125° | 115° / 126° / 136° |
| Maximum load | 136 kg | 136 kg | 136 kg | See product page |
| Recommended user height | 150–190 cm | 150–190 cm | 145–180 cm | See product page |
| Base | — | Plated steel | PA | 330 mm PP (chrome on the M59Pro-S) |
| Chair weight | 17.2 kg | 20.2 kg | 14.7 kg | See product page |
"See product page" marks values we have not yet confirmed, so we have left the numbers out. Open the M18 / M57 / M59AS / M59Pro comparison for the latest data side by side.
M18 vs M57: foam seat or full mesh
The difference you feel the moment you sit down is the seat. The M18 uses an 8 cm memory-foam seat in a W shape that cradles your hips and thighs softly. People who have found that the edge of a mesh seat presses into their legs, or who just never got used to mesh, often prefer the M18.
The M57 is mesh on both seat and back, so it breathes better in Thailand's heat and humidity, and it adjusts more precisely: 3D armrests (7 cm height, 6 cm forward/back, 17.5° swivel) and 2D lumbar support that moves for both height and depth, so you can line it up with your back more exactly. A plated steel base and a 20.2 kg frame also make it the most solid-feeling chair here.
In short: if you run warm, sit for long stretches and like fine adjustment, choose the M57. If seat softness matters most and your budget is tighter, the M18 is better value, and it comes in a footrest version too.
There are several M59s. Which one?
The M59 name confuses a lot of people, because the website lists the M59AS, Smart M59, Smart M59Pro, M59Pro-FT and M59Pro-S. Think of them as two lines.
M59AS: high back, self-adjusting lumbar, good for small spaces
The M59AS has a tall, wide backrest, an Auto Adaptive lumbar pillow that settles against your back on its own, and armrests that flip back and rotate 90°, so the chair tucks well under a desk. That suits small rooms and condos. Its recommended user height is 145–180 cm, which makes it a good choice for small to medium builds, and at 14.7 kg it is the lightest chair in this article.
Smart M59 / M59Pro: the deepest recline, with a footrest option
The Smart line uses spring lumbar support that adapts to your back, flip-up 3D armrests and a mechanism that locks at 115°, 126° and 136°, the deepest recline of the group. It has a TÜV Class 3 gas lift that the product page lists as BIFMA certified. The M59Pro-FT adds a built-in footrest and the M59Pro-S switches to a metal base. A good fit if you like to lean back or game between tasks.
Pick by what matters to you
| You want… | Consider |
|---|---|
| a soft seat rather than mesh | M18 |
| to stay cool through long sessions, with fine adjustment and a sturdy frame | M57 |
| a chair for a small room or narrow desk, for a small to medium build | M59AS |
| to recline, game and put your feet up | Smart M59Pro-FT |
| a metal base | Smart M59Pro-S |
What all of them share
- They are ergonomic chairs with adjustable seat height, recline, headrest and lumbar support.
- The backrest is breathable mesh.
- You assemble them yourself (instructions are in the box, and it does not take long).
- None of them lists seat-depth adjustment. If you are very short or very tall and want to adjust seat depth, step up to the Doro family, such as the Doro C100.
Three things to do once your chair arrives
- Set the seat height first, so your feet rest flat and your knees are roughly level with your hips.
- Line the lumbar support up with the curve of your lower back. On the M57 adjust both height and depth; on the M59AS just sit fully back and let the pillow settle against you.
- Pick a recline angle for the task: the first lock position for typing, and unlocked for a deeper lean when you take a break.
For every setting step by step, see how to adjust an ergonomic chair properly.
Is it worth stretching to a Doro?
If you sit 4–6 hours a day, the M series already does the job well. If you sit 8 hours or more every day, or regularly get lower-back pain, the automatic lumbar support and seat-depth adjustment of the Doro family may be worth the extra over time. Read Doro S100 vs C100 vs C300 next.
The bottom line
The M18 is an affordable ergonomic chair with a soft seat. The M57 is full mesh, the most adjustable and the sturdiest of the group. The M59 family splits into the space-saving M59AS and the Smart M59Pro, which reclines deepest and offers a footrest. Still unsure? Try the Chair Finder or book a showroom visit.
