An oximeter has a housing configured to have a cavity defining portion that is adapted to be fitted with covers of various dimensions to effect receptacles of different dimensions for accommodating differently sized sensor of sensor assemblies that are matable to the oximeter for sensing physical attributes of a patient. Each of the covers, once fully fitted to the housing, is fixedly latched thereto unless a force that overcomes the latching is applied to remove the cover. The effected receptacle is adapted to biasedly retain a corresponding sensor placed therein. The holstered sensor therefore would not accidentally fall out or be removed from the receptacle, until the user deliberately applies a force to remove the sensor from the receptacle.