This apparatus, described in BS 4745:2005, measures a sample of textile, either between two metal plates (for underclothing) or between a metal plate and free air (for outer layers).
The described instrument, according to BS 4745:2005, determines the weight of a fabric sample, either by pressing it between two metal sheets (suitable for intimate apparel) or by weighing it against a metal sheet and ambient air (more suitable for outer garments).