A wearable gear for holding a physiological sensor for monitoring a subject, such as a pulse oximeter. Said wearable gear being configured to automatically adjust the maximal length such that the predefined tension is obtained regardless of the size of the body part of the subject. The wearable gear comprises a tensioning element having a maximal length, a holding unit for holding the physiological sensor, the wearable gear further comprises a tension mechanism for tensioning the tensioning element to a predefined tension when at least partially around a body part of the subject, wherein the tension mechanism comprises i) a first part comprising a resilient material, and ii) a second part comprising a non-resilient material, and wherein the first part and the second part mechanically cooperate with each other to automatically adjust the maximal length such that the predefined tension is obtained regardless of the size of the body part.