Double relaxation oscillation superconducting quantum interference devices (DROSs) with a gradiometric signal SQUID and either a reference SQUID or a reference junction will be presented in this article. The devices are user friendly, particularly those with a reference junction. Because of the large flux-to-voltage transfer of∂V/∂&Fgr;=0.7–1 mV/&Fgr;0,the devices can be operated in a flux locked loop based on direct voltage readout without loss of sensitivity. The typical white flux noise of the DROSs amounts to&sqrt;S&Fgr;=5–6&mgr;&Fgr;0/&sqrt;Hz,which corresponds to an energy resolution&egr;=S&Fgr;/2Lsq≃200 h.Coupled to an external planar first-order gradiometer, a white magnetic field sensitivity of&sqrt;SB<2 fT/&sqrt;Hzwas measured inside a magnetically shielded room. ©1997 American Institute of Physics.