Strain Relief Kit for Fiber Rack Mount Enclosures, 2U+Description Strain Relief Kit, 2U and Larger Fiber Rack Mount Enclosures The strain relief kit is designed to be installed onto any FB23 rack mountable fiber distribution unit that is 2U or larger. The strain relief kit gently guides fibers into the unit to avoid the strain of sharp angles. The kit includes all mounting hardware and three grommet sizes. Features Physical Properties Diameter: 0. 300" 0. 79" Material: Power coated steel, rubber grommets