Implantable medical leads and/or lead extensions include a band that encapsulates a portion of conductors of the lead and/or lead extension. The band may be reflowed in order to provide the encapsulation of the conductors. The band may further be used to create a seal together with the surrounding lead body and an additional object such as a stiffener rod, stylet tube, and/or molding stylet, to allow a proximal area of a lumen of the lead body to be injection molded while prevent the injection molding material from proceeding past the band. When a stiffener rod is present in a proximal area of the lead and/or lead extension, additional stiffness is provided to the lead body to resist buckling of the lead body during insertion of the proximal end. The band may be bonded to the stiffener rod to fix the position of the stiffener rod relative to the conductors.