The Neutrik Hinged Cover for D-Size Chassis - Blue is intended to protect hinged, chassis connector and receptacles from water, dust and dirt in unmated condition. The covers are color-coded to be easily distinguishable based on specific application like SCDX cover ;Black IP protection, multimode SCDX-5 green IP protection, single mode; APC; SCDX-6 blue IP protection, single-mode PC; and SCDX-9 white IP protection.