Whirlwind FP-4 unit feature removable bottom and end panel(s) to facilitate custom punching and engraving. Cable-clearance slots in the doors allow it to close over cables when in use and the FP-4 features a second separate hinged section that can remain open if the pocket is used with large diameter cable. FP-3 is deep enough to contain multipin connectors including Whirlwind's MASS series.