SIHOO - C300 Ergonomic Office Chair with Soft 3D Armrests, Dynamic Lumbar Support, Adjustable Backrest - Gray
About this product
The SIHOO A3 office chair, an innovative ergonomic model, uses advanced technology to ensure comfortable sitting and proper posture. It features automatically adjustable 4D headrest, lumbar support, linked 3D armrests, an intelligent gravity mechanism, and automatic adjustment, along with a soft backrest and breathable mesh seat for all-day comfort. Its 3D headrest offers wide-angle adjustment (4.5cm up/down, 6.5cm forward/backward, 20° angle) and is made of soft mesh with a triangular soft elastic frame and support straps for back support; the 4-position adjustable 6cm liftable backrest suits all heights and auto-reverts to level 1 when at maximum height. It also comes with domino auto-adaptive lumbar support. The intelligent gravity mechanism with weight-adjustable resilience enables 2-step auto-adjustment and tilting from 92° to 100° to 112° (max), allowing comfortable rocking or short breaks. Certified by American BIFMA and German TUV, it has passed tests like backrest strength and seat impact tests, and is equipped with SGS Class 4 cylinders for durability and safety. It comes with a 3-year warranty, with support available for any product issues.
Color
GrayFeatures
Innovative Ergonomic Chair
SIHOO's latest ergonomic office chair uses advanced technology to ensure comfortable seating and healthy posture. It features an auto-adjusting 3D headrest, adaptive lumbar support, synchronized 3D armrests, and an intelligent weight-sensitive mechanism. With a soft backrest and breathable mesh seat, it delivers lasting comfort even during long hours of use.
Safety certification
The SIHOO A3 office chair is BIFMA and TÜV certified, passing rigorous tests for backrest strength, seat impact, caster durability, and leg strength. It features an SGS-certified Class 4 gas lift for enhanced safety and comes with a 3-year warranty. Contact us with any product concerns for complete peace of mind.
Wide Angle Adjustable Headrest and Trackable Backrest
The SIHOO A3 office chair features a 4D headrest that adjusts 4.5cm vertically, 6.5cm horizontally, and 20° in angle. Its triangular elastic frame with dual support straps cradles your back from shoulders to lumbar. The 4-position backrest adjusts up to 6cm in height and auto-resets when raised fully, fitting all users securely.
Domino auto-adaptive lumbar support and 4D linkage armrest
The SIHOO A3 features a 4D auto-adjusting headrest (4.5cm vertical/6.5cm horizontal/20° tilt). Its triangular elastic frame with shoulder-to-lumbar support straps and 4-position backrest (6cm height, auto-reset) ensures ergonomic comfort for all users.
Intelligent gravity mechanism・Automatic adjustment function
The SIHOO chair's tilt mechanism is its core innovation. Its intelligent gravity system automatically adapts to any user's weight with 2-step adjustment. Recline seamlessly between 92°, 100°, and 112° for comfortable rocking or deep relaxation during breaks.
Specifications
- Product Height41.34 inchesProduct Width27.56 inchesProduct Depth27.56 inchesSeat Height (From Floor)17.72 inchesMaximum Weight Capacity330 poundsMaximum Seat Height From Floor17.72 inches
Reviews
Rating 5 out of 5 stars with 3 reviews
The vast majority of our reviews come from verified purchases. Reviews from customers may include My Best Buy members, employees, and Tech Insider Network members (as tagged). Select reviewers may receive discounted products, promotional considerations or entries into drawings for honest, helpful reviews.
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The SIHOO A3 office chair, an innovative ergonomic model, uses advanced technology to ensure comfortable sitting and proper posture. It features automatically adjustable 4D headrest, lumbar support, linked 3D armrests, an intelligent gravity mechanism, and automatic adjustment, along with a soft backrest and breathable mesh seat for all-day comfort. Its 3D headrest offers wide-angle adjustment (4.5cm up/down, 6.5cm forward/backward, 20° angle) and is made of soft mesh with a triangular soft elastic frame and support straps for back support; the 4-position adjustable 6cm liftable backrest suits all heights and auto-reverts to level 1 when at maximum height. It also comes with domino auto-adaptive lumbar support. The intelligent gravity mechanism with weight-adjustable resilience enables 2-step auto-adjustment and tilting from 92° to 100° to 112° (max), allowing comfortable rocking or short breaks. Certified by American BIFMA and German TUV, it has passed tests like backrest strength and seat impact tests, and is equipped with SGS Class 4 cylinders for durability and safety. It comes with a 3-year warranty, with support available for any product issues.

SIHOO C300 Pro V2 – A New Era of Adaptive Comfort. Real comfort moves with you — and the C300 Pro V2 is engineered to do exactly that. Whether you're leaning forward to type or sitting back to think, its DynaCore Full-Body Support system responds to every shift, keeping your spine aligned and your body at ease. The SynchroFlex Backrest molds to your unique spinal curve, spreading pressure evenly across your back so you stay comfortable from your first coffee to your last email. With Smart Gravity Response that automatically adjusts recline resistance to your weight, plus an intuitive right-side control for height, tilt, and seat depth, this chair adapts effortlessly to your body. The Self-Adaptive Lumbar Support 2.0 acts like a second pair of hands, actively hugging your lower back to eliminate gaps and prevent strain. Paired with a 3D Superwide Headrest and 8D Bionic Armrests, it delivers full upper-body support that keeps you focused, relaxed, and ready for anything — whether you're working, gaming, or simply unwinding.

The Sihoo Doro C300 Pro Ergonomic Office Chair redefines comfort with its multi-functional adjustable design, featuring a 3D headrest, adaptive lumbar support, ultra-soft 6D armrests (adjustable in five directions), seat depth adjustment, intelligent weight-sensing reclining mechanism, and breathable mesh fabric for all-day comfort. Its adaptive dynamic lumbar support moves with your body to relieve back pain, while the wider seat and 105°-135° recline range cater to taller users and relaxation needs. The height-adjustable backrest (with 2.36" travel) and flexible triangular frame provide continuous support as you shift positions. Certified by EU REACH, EN1335, German TUV, and US SGS BIFMA standards, this chair boasts 12 patents and a SGS-certified 4-stage pneumatic lift for durability. Backed by a 3-year warranty, we offer free replacement parts—experience next-level ergonomic support with the Doro C300 Pro.

Imagine a chair that doesn't just sit there—it sits with you. Whether you're grinding through spreadsheets in your home office, catching up on emails from the living room, or diving into a weekend movie marathon in your entertainment room, the SIHOO B100 ergonomic office chair is designed to move, breathe, and adapt to your life. Let’s start with your back. The adaptive dynamic lumbar support features a spring-loaded pillow that gently responds to every shift in your posture. Lean forward to type—it supports. Sit back to think—it follows. It’s like having a co-pilot for your spine, helping maintain your natural S-curve whether you're deep in focus or just taking a breath. Now, imagine this: you’ve just finished a long day of back-to-back meetings. You wheel your desk chair away from the monitor, recline to 135°, and pull out the built-in footrest. Suddenly, your office chair becomes a lounge chair. That’s the kind of versatility this mesh chair offers. With three recline angles—110° for work, 125° for casual conversation, and 135° for full-on chill mode—it transitions as smoothly as you do. The extra-wide 2D headrest adjusts to your height, so your neck never has to strain. The flip-up armrests let you tuck the chair completely under most desks when not in use—perfect for tight spaces in a bedroom or studio apartment. And when you're gaming or watching movies, the arms recline with you, keeping your shoulders relaxed and your focus intact. Worried about heat? The full-mesh chair back breathes like linen. Air flows through freely, so you stay cool even during intense gaming sessions or long writing sprints. The pressure-relief cushion is thoughtfully designed to distribute your weight evenly, reducing discomfort in your hips and thighs—especially important if you're spending hours in your computer chair. This isn't just a pretty seat. It's built to last. With a reinforced frame and a heavy-duty base, this big and tall office chair supports up to 300 lbs, offering stable, quiet performance whether you're rolling across hardwood or carpet. The tilt mechanism is smooth and silent—so, so no one in the next room will hear you lean back during a Zoom call. From your home office to your entertainment room, from Zoom meetings to movie nights, the SIHOO B100 is more than just an executive chair—it's your personal comfort zone, ready whenever you are. Backed by a 3-year warranty and 30-day returns, it's comfort you can count on.










































