The HD Flex™ Fiber Enclosure is 1 RU and is configured with sliding front-access drawers to accept up to eighteen 4 port HD Flex™ cassettes or Fiber Adapter Panels for a maximum density of 144 fibers. The HD Flex™ Fiber Enclosure is 1 RU and is configured with sliding front-access drawers to accept up to eighteen 4 port HD Flex™ cassettes or Fiber Adapter Panels for a maximum density of 144 fibers.