Abstract: A wearable band of a size and length suitable to be positioned around a limb, or other body part, of a user, said band comprising a flexible bistable strip movable between a first state, in which it is substantially axially straight, and a second, ring-like state, and having a yield point, said band being configured such that generally radial application of pressure exceeding said yield point to an end of said hand causes it to move, under its own tension, from said first state to said second state, wherein a portion of the length of said bistable strip at a free end thereof has a progressively reducing width and/or thickness such that the tensile force in said portion, when said band is in said first configuration, gradually lessens along said portion toward said free end.