Cable managers of the present invention include a panel, at least two adjacent spaced-apart projections, which define an opening therebetween, and a tab connected to at least one of the projections. The tab assists in cable routing and retention. In one embodiment, the tab extends to a distance at least midway between a top surface of the one projection and the bottom surface of the other projection. In another embodiment, a distance between a top surface of the tab on one projection and the bottom surface of another adjacent projection is between about 0.10 inches and about 0.30 inches. In yet another embodiment, a cable manager comprises separable portions, and at least one spacer member which is adapted to be attached to each of separable first and second portions. The spacer member increases the width of the manager to provide additional space to run cable within the manager.