All of these high-impact plastic spools are used to neatly guide and retain cable or jumper wires. Cabling is held in place by the spool's rim to allow easy access for changes or modifications. The S20A and S20B are white and can be used with either a main cross-connect frame or backboard. The S20C is black to match our CC frames and modular patch panels, and screws directly into the mounting holes of a standard 19 or 23 inch relay rack.