7. The improvement of claim 1 wherein a) the compression insert has a first substantially flat planar bottom surface engaging a second substantially flat planar bottom surface of the longitudinal connecting member, the connecting member being made from a polymer and having a substantially flat top planar surface; and further comprising b) a one-piece closure structure having a third substantially flat planar bottom surface in direct contact with both the compression insert and the top planar surface of the connecting member.
7. The improvement of claim 1 wherein a) the compression insert has a first substantially flat planar bottom surface engaging a second substantially flat planar bottom surface of the longitudinal connecting member, the connecting member being made from a polymer and having a substantially flat top planar surface; and further comprising b) a one-piece closure structure having a third substantially flat planar bottom surface in direct contact with both the compression insert and the top planar surface of the connecting member. 8. The improvement of claim 7 further comprising at least one recessed relief surface formed in the compression insert, the recessed relief surface receiving material flow of the longitudinal connecting member.