This elastic nylon bicep band is Compatible with Google Fitbit Air, serving as a practical arm band alternative to traditional wrist straps. Constructed with soft stretch woven nylon, the arm band delivers high breathability and fits closely to arms without restricting natural movement during activity. Equipped with an integrated metal frame, it firmly holds your tracker to avoid shifting or dropping when exercising; the metal frame is detachable for installation on other fitbit arm bands effortlessly. Designed with a metal sliding buckle and 5 widened hook-and-loop fasteners, this bicep supports smooth stepless adjustment with a size range of 9-16.5 in (total length 42 cm). It can be worn on biceps or wrists to meet different usage demands, perfectly matching workout, running and cycling. Only the replacement arm band is contained in the package; tracker and charging accessories are not included.