Adjustable armrests and additional controls for seat and/or backrest adjustment are now available as options on these Class 10 chairs. The selection increases opportunities for customizing basic Class 10 models to meet the exact requirements of individual users and specific high-tech applications. Armrests are both height and width adjustable and have either upholstered or self-skinned urethane pads. Adjustability increases the armrests’ capability to provide proper arm support that can greatly reduce shoulder, back and neck strain from prolonged seated work. The adjustability also adds to a chair’s flexibility in providing comfort and support for multiple users. Chairs and stools can be made with a patented Microtech filtration system within the seat cushion. The filtration system replaces an air exchange system with a bag encased in a pan attached to the seat. The new system preserves the original appearance of the chair model while trapping particulates and allowing the seat to conform to body shape.