Does the HON Ignition 2.0 ReActiv Mid-Back Task Chair have adjustable height?

Yes, it has pneumatic seat-height adjustability that accommodates various body heights, ranging from 17.25" to 21.75".

What is the material used for the seat of the HON Ignition 2.0 ReActiv Mid-Back Task Chair?

The seat of the HON Ignition 2.0 ReActiv Mid-Back Task Chair is made of Basalt Vinyl.

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HON Ignition 2.0 ReActiv Mid-Back Task Chair - 17.25" to 21.75" Seat Height - Basalt Vinyl Seat - Charcoal Back, Black Base (HONI2MRL2BS23TK)

ReActiv, low-back design—perfectly balanced support for full zonal comfort.
Height-adjustable, back-cushion-style lumbar support.
Pneumatic seat-height adjustability accommodates various body heights.
Synchro-tilt mechanism with seat slider for a full range of reclining positions.
Tilt tension controls the rate and ease of recline.
Upright tilt lock secures the chair in a full upright position.
Adjustable arms put a little extra support right where needed.