The invention provides compositions and methods useful for identifying, verifying or authenticating any type of sample, whether the sample, is biological or non-biological. The safety circuit arrangement also has a signaling device, which is connected to the control device via a two-wire line having a first core and a second core. Then, an abutting part, at which each of the cam projections contacts with a spring piece part of a corresponding one of the first brushes, gradually moves to an end of the first brush. An improved staple construction of increased rigidity is also shown.