4-Star refers to the number of pronged feet at the bottom of a work chair base. A 4-Star Base is typically provided with glides (pads that protect floor surfaces) and therefore is suited for relatively static environments.

5-Star refers to the number of pronged feet at the bottom of a work chair base. This has become the universal standard for most office chairs as it provides improved stability. Depending on model specifications, 5-Star Bases may be provided with glides (pads that protect floor surfaces and render the chair relatively static) or rolling casters (wheels that render the chair relatively mobile).

Tilt Lock allows the chair seat to be 'locked', preventing it from tilting backwards, or unlocked, allowing it to tilt backwards without restrictions.

Tilt Limiter and Seat Angle refers to the adjustable seat back and adjustable seat pan, respectively. The Tilt Limiter allows the user to select the tilt range to limit the amount of recline in the seat back . When the user leans back on the seat back, the maximum it will recline is to the angle set by the tilt limiter. The Seat Angle allows the user to set either a horizontal or 4° forward angle of the seat pan, allowing the thighs to rest horizontally or slightly angled down in relation to the floor. These features help to customize the chair to the user's body, aiding in lower back support and all day comfort.

The Tilt Limiter allows the user to select the tilt range to limit the amount of recline in the seat back. The user can adjust the Tilt Limiter by leaning all the way forward and moving an adjustment level up to find different stopping points. When the user leans back, the seat back will stop reclining at the angle that was last set.

Tilt tension controls the amount of force required to recline. Tension can be increased or decreased until the chair back resistance is set to the user's preference for working comfort and should take in to account how the user moves throughout the day.

Harmonic Tilt™ transfers weight from the seat to the back without changing the relationship between the chair's back and the user's back. This patented mechanism keeps resistance consistent throughout the recline range. It allows the user's body to pivot naturally at the ankles, knees, and hips. It provides balanced support as the user moves from an upright posture to a completely reclined posture and as it stops anywhere within that recline range. Harmonic Tilt is available on all Mirra and Celle models.

Pneumatic Seat-Height Adjustment regulates the height of a chair relative to the floor using a gas lift mechanism, usually controlled by a lever. It allows the user to adjust a custom seat-height based upon the size of the user. This reliable adjustment mechanism has become an industry standard because of its ease of use and quiet, smooth operation.

Ganging Connectors attach adjacent chairs to form a unitary row of seating. This is a useful feature for auditorium or conference seating configurations where standard rows or sets of chairs are needed.

FlexNet™ is a strong, mesh-like material specifically developed for the Caper Chair. Similar to the Aeron Chair's Pellicle suspension, FlexNet provides aeration as well as added comfort and weight distribution for longer-term sitting.

TriFlex™ is a bendable, elastic material developed for the seat back of the Mirra Chair. It provides flexible and continuous back support intended to support the entire spine while providing airflow. TriFlex is self-adjusting, conforming to the user as soon as he/she is seated.

AireWeave™ seat-suspension material was developed for the seat of the Mirra Chair. It is lightweight and breathable and evenly distributes the user's body pressure over the seat of the chair, while keeping the user cool. AireWeave is self-adjusting, conforming to the user as soon as he/she is seated.

Pellicle® was developed for the Aeron Chair. It is a material that conforms to the user's body and retains its original shape when unoccupied. The material is lightweight and breathable and distributes the user's weight evenly over the seat and back of the chair.

Cellular Suspension™ seat and back material was created specifically for Celle Chairs. It uses pliable molded polymer "cells" and loops to responsively flex in concert with the body's movements throughout the workday. This lightweight, breathable material evenly distributes the user's weight over the seat and allows the back to provide flexible and continuous support.

Pixelated Support Technology refers to the seat construction of Herman Miller's Embody Chair. This 4-layer construction provides support and comfort by spontaneously conforming to the user's shape and postural movements, while simultaneously moving heat away from the body. The results are improved circulation and greater comfort.

FlexFront™ Seat Depth was developed for the Mirra Chair. By squeezing a handle under the front of the seat, users can control seat depth by curling the front edge of the seat up or downward, providing a 2" range of adjustment. And, because depth is controlled by the shape of the seat front and not a moving seat pan, there is never a gap between the chair seat and back. When properly adjusted, the seat edge should not touch the back of the user's legs. This ensures the best body alignment, providing constant spine support and all day comfort.

Kinemat® Tilt is adjusted by turning a knob under the Aeron Chair's seat pan. The feature promotes a reclining posture by using a tilt geometry based on human body linkages moving through space. This engineering opens up the angle between the thighs and torso encouraging a reclined posture that aids in back and body support. Kinemat allows the body to naturally pivot at the ankles, knees, and hips by responding to the user's movements and maintaining full chair support of these pivot points. (Imagine the many body shifts and position changes a user makes throughout the work day. Kinemat is designed to adjust with all these changes, as they occur, without compromising comfort or posture.)

Aeron's PostureFit® Support provides a custom fit in the lower back area, below the beltline. A step up from standard lumbar supports, PostureFit is flexible and follows the shape of the lower back. By allowing the pelvis and base of the spine to sustain a forward position, it promotes a healthier posture and improved lower back comfort and sacral support. This features comes standard with the Aeron Posture fit Work Chair.

Mirra and Celle Chairs use Passive PostureFit® Support. A camber shape at the base of the back creates an arched area that supports the way the user's pelvis tilts naturally forward, so that the spine stays properly aligned, whether the user leans back or forward. By allowing the pelvis and base of the spine to sustain a forward position, it promotes a healthier posture and improved lower back comfort and sacral support. Passive PostureFit is available on all Mirra and Celle models as an integrated feature.

Height Adjustable Arms

Height-Adjustable Arms allow the user to set chair arms at varying vertical positions (moving the armpads up or down). Adjustable arms add to the versatility of the chair allowing a user to slide the chair under a desk, adjust the arms for proper arm support (moving weight off the shoulders), etc. Chairs noted as "fully adjustable" feature arms that move vertically and also pivot (the armpads move at a set degree-range outward and inward from the user). Adjustable spans vary by model.

Seat Depth is measured from the front of the seat to the chair's back support. For fixed seat depth chairs, this distance can not be altered or customized for the user. Therefore, the seat will fit everyone differently depending on the length of their legs. The depth of the seat varies by model.

Adjustable Seat Depth allows the user to customize the seat distance, measured from the hip to the knee, to help adjust for user's leg length. To adjust, the user presses a lever and slides the entire seat pan back or forward to customize the amount of support and to create the optimal fit based on their body.

Adjustable Lumbar Support allows the user to change the seat back shape along the base of the seat back to enhance support and comfort of the user's lumbar region. Lumbar adjustments vary by model. But, in general, these mechanisms are controlled by levers to adjust to fill the void left between the chair and the curve in the user's mid-back or lumbar region.

Glides are specialized pads at the base of a chair or other piece of furniture which protect the floor beneath and make it easier to occasionally reposition the chair. However, glides render the chair mostly static within its space.

Casters are rolling wheels located at the base of a chair or other piece of furniture making it fully mobile and moveable within its space. Different caster options are available on some chairs to accommodate movement on different types of flooring materials (for example, hard floors or carpet).

Fixed Arms are non-adjustable. Consider desk-top height and arm positioning needs when selecting chairs with this feature.

The Mirra Chair's 3-Dimensional Adjustable Arms allow the user to adjust arms 4" vertically, 1.4" horizontally, and pivot the arm pads 11° outward and 11° inward. Adjusting arms vertically can add to the versatility of the chair allowing a user to slide the chair under a desk or to raise the arms for arm support. Adjusting arm pivot (or angle) can help support different types of work and shifts in posture. For example, the user might adjust chair arms inward for support while using a keyboard or adjust arms out for support when using a mouse. While horizontal arm adjustment tailors the chair so that user arms are fully supported, taking weight off the shoulders.

Adjustable Seat Height regulates the height of a chair relative to the floor. This feature, usually controlled by a lever, allows the user to adjust a custom seat-height based upon the size of the user. Seat height should be adjusted so the user's feet are flat on the floor with knees at a comfortable bend where the lower legs and hips are a little over 90° with the thighs sloping slightly downward.

Kinematic Spine™ technology was designed for the Setu Chair. It is a frame technology integrated into the chair's back to allow for varying recline positions and continuous support. This feature is self-adjusting and requires no user adjustment.

A self-adjusting feature requires no manual adjustment by the user.