Use of a headband to indicate tension and system comprising an oximetry sensor and a headband

The elastic segment (102) by which a size decision was made to fitting the circumference of a wearing person's head, The headband (102) with a tension indicator (110) which has an inelastic segment (104) attached to an elastic segment (102) smaller than an elastic segment (102) is offered. While a size decision of the inelastic segment (104) is made to attaining to a part of elastic segment (102) when an elastic segment extends, and the elastic segment (102) is not extending, An inelastic segment (104) is larger than the elastic segment (102) portion which the inelastic segment has attained to. In the style that the loop (110) which an inelastic segment (104) projects from the surface of an elastic portion when the headband is not fastened enough, and shows by this that re-bolting of a headband is required visually is formed, An inelastic segment (104) is attached to an elastic segment.