Abstract: An electrical outlet box, for mounting in an opening of a panel, includes holding members that are rotatably and slidably mounted upon a cylindrical pin fixed to the base of the housing and extending towards the open front thereof. The holding members are rotatable from an inoperative position wherein the holding member is substantially inside the housing to an operative position wherein the holding member projects through an aperture in the housing sidewall. Each holding member is slidable forwardly upon its respective pin to bear against the back side of the panel. Retention elements allow forward movement of the holding member but resist rearward movement, and guide elements guide the holding member during forward movement.