A flexible connection unit for use in a spinal fixation device, including: a first end portion and a second end portion, at least one of the first end and second end configured to be engagable by a section of a first bone securing member; a flexible member located between the first and second ends, the flexible member permitting motion of the first end relative to the second end; and a transition area located between the first end and the flexible member, the transition area tapering in diameter from a first section of the transition area proximate to the first end toward a second section of the transition area proximate to the flexible member.