Office chair Topstar Sitness 40 ST290W51 Red — ergonomic design, adjustable height

Topstar Sitness 40 ST290W51 Red is an ergonomic office chair designed for daily desk use. The chair features a flexible seat mechanism that promotes active sitting and supports natural posture adjustments. With adjustable seat height and a contoured backrest, this red office chair is intended for home and office environments where users need reliable basic comfort and mobility during extended periods at a workstation.

Advantages

The chair’s sitness mechanism encourages micro-movements of the pelvis and spine to reduce static load on the lower back. Height adjustment allows adaptation to different desk heights and user sizes, while the contoured seat and backrest provide simple, supportive seating. Smooth casters and a swivel base enable easy repositioning and access to surrounding work areas without standing up.

Suitable for

• Home office work and study
• Standard office desk tasks and meetings
• Short to medium duration computer sessions
• Users seeking a compact ergonomic chair with mobility

Key specifications

• Ergonomic sitness seat mechanism for active sitting
• Adjustable seat height via gas lift
• Contoured seat and backrest for lumbar support
• Swivel base with rolling casters for mobility
• Upholstery in red fabric
• Suitable for standard desk heights and typical adult body sizes

How to use

Adjust the seat height so that your feet rest flat on the floor and your thighs are approximately parallel to the floor. Sit with your back against the contoured backrest to take advantage of the sitness mechanism: small forward and backward movements of the pelvis are allowed and supported to reduce stiffness. Use the swivel and casters to reach items around your workspace without twisting your torso excessively. Avoid prolonged static postures by changing position periodically.

Usage recommendations

For best results, combine regular posture changes with short standing or walking breaks. If multiple users will use the chair, adjust seat height before each session to maintain ergonomic alignment. Inspect the casters and gas lift periodically for smooth operation and safety.