The transmission coefficient of metamaterial structures, which include a combined system of a single split ring resonator and wire (SRRW) and that of a closed-SRR and wire (CRRW), has been studied by varying the width of the continuous wire. Our numerical results support the analytical arguments made by Koschny et al. (Phys. Rev. Lett., 93 (2004) 107402), i.e., the combined electric response of the SRRW system was approximately identical to that of the corresponding CRRW system. It is important to note that a better picture of transmission and index of refraction can be presented by considering three distinct regions, i.e., fm > f′p, f′m > f′p > fm and f′p > f′m, which appear in order by increasing the width of the wire. This is because only the case of f′p > f′m was considered in the previous works.