1. Important Safety Information
Please read all instructions carefully before assembly and use. Keep this manual for future reference.
- For your safety, do not stand on this chair.
- Ensure all screws and bolts are securely tightened before use.
- Do not use the chair on uneven surfaces.
- Maximum load capacity: 300 lbs. Do not exceed this weight limit.
- Allow ±1.5cm/0.6inch errors in seat height due to manual measurements.
2. Product Overview
The Yaheetech Charles Ergonomic Office Chair is designed for comfort and support in your workspace. It features a breathable mesh back, adjustable lumbar support, a thick cushioned seat, and smooth-rolling casters.

Image: Front and side view of the Yaheetech Charles Ergonomic Office Chair in blue.
3. Setup and Assembly
Assembly is required. Please follow these steps carefully. All necessary tools are included.
3.1 Components Checklist
- 1 x Seat Cushion
- 1 x Backrest
- 1 x Gas Lift Cylinder
- 1 x Star Base
- 5 x Casters
- 2 x Armrests
- 1 x Mechanism Plate
- Hardware (screws, washers, Allen wrench)
3.2 Assembly Steps
- Attach Casters to Star Base: Insert each caster into the holes at the end of the star base legs until they click securely into place.
- Insert Gas Lift: Place the gas lift cylinder into the center hole of the assembled star base.
- Attach Mechanism Plate to Seat: Align the mechanism plate with the screw holes on the underside of the seat cushion. Ensure the 'FRONT' marking on the mechanism faces the front of the seat. Secure with screws and washers using the provided Allen wrench.
- Attach Armrests to Seat: Align the armrests with the designated holes on the sides of the seat cushion. Secure with screws. Do not fully tighten yet.
- Attach Backrest to Armrests: Align the backrest with the remaining holes on the armrests. Secure with screws. Once all screws are in place for the armrests and backrest, tighten them fully.
- Connect Seat Assembly to Gas Lift: Carefully place the assembled seat (with armrests and backrest) onto the gas lift cylinder, ensuring it sits firmly in the mechanism plate.
Video: This video demonstrates the installation of office chair legs, which is a key step in the assembly process.
4. Operating Instructions
4.1 Adjustable Seat Height
To adjust the seat height, locate the lever under the seat on the right side. Pull the lever up while sitting on the chair to lower the seat, or pull it up while standing to raise the seat. Release the lever to lock the height.
4.2 Reclining Function and Tilt Tension
The chair can be tilted and leaned backward. To activate the reclining function, pull the lever under the seat outwards. To lock the chair in an upright position, push the lever inwards. The tilt tension control knob, located under the seat, allows you to adjust the resistance of the recline. Turn clockwise to increase tension (stiffer recline) or counter-clockwise to decrease tension (easier recline).
4.3 Lumbar Support
The chair features fixed lumbar support designed to follow your spine's natural curve, promoting proper posture and reducing back strain.

Image: Close-up view highlighting the fixed lumbar support and breathable mesh backrest for enhanced comfort.
4.4 360° Swivel and Rolling Casters
The chair is equipped with a 360° swivel function and smooth-rolling casters, allowing for easy movement and flexibility around your workspace.
Video: This video showcases various features of the chair, including its adjustability and mobility.
Video: This video provides a durability overview of the chair's construction and materials.
5. Maintenance
5.1 Cleaning
Wipe clean with a damp cloth. Avoid harsh chemicals or abrasive cleaners that may damage the materials.
5.2 Regular Checks
Periodically check all screws and bolts to ensure they remain tight. Re-tighten if necessary to maintain stability and safety.
6. Troubleshooting
6.1 Chair Not Adjusting Height
- Ensure the gas lift lever is fully engaged.
- Check if the gas lift cylinder is properly seated in the base and mechanism plate.
6.2 Wheels Not Rolling Smoothly
- Check for any debris (hair, dust, etc.) caught in the casters and clean them.
- Ensure casters are fully inserted into the star base.
6.3 Instability/Wobbling
- Verify all assembly screws are securely tightened.
- Ensure the chair is on a flat, even surface.
7. Specifications

Image: Detailed diagram showing the dimensions of the Yaheetech Charles Ergonomic Office Chair.
| Feature | Detail |
|---|---|
| Model Name | Charles |
| Color | Blue |
| Material | Alloy Steel, Iron, Polypropylene, Polyester Mesh, Foam, Non-woven Fabric, Plywood |
| Overall Dimensions | 24.5″ W × 24″ D × (35-39)″ H (62.2cm W x 61cm D x 88.9-99.1cm H) |
| Adjustable Seat Height | 18-22″ (45.7-55.9cm) |
| Max. Load Capacity (each) | 300 lbs (136 kg) |
| Special Features | Adjustable Height, Arm Rest, Ergonomic, Lumbar Support, Reclining, Swivel |
| Back Style | Open Back, Mesh |
| Unit Count | 2.0 Count (for the 2-pack product) |
| Item Weight | 45.8 pounds (20.8 kg) |
8. Warranty and Support
For warranty information or customer support, please refer to the documentation included with your purchase or contact Yaheetech directly. Extended protection plans may be available for purchase.





