Delivery of more than one therapeutic fluid as a means to control symptoms of a health conditions is disclosed. Both the knuckle and the retainer have recesses and the retainer is arranged in both recesses upon assembly. Without reconfiguring the host’s operating software, the system employs a method to respond to and satisfy a host inquiry for the storage device’s identification information by employing the special data structure. Then the multi-attribute communication feature vectors are clustered. Preferably, in at least a portion of the head tube, the wall thickness is thicker in a forward side than the thickness in a rearward side.