The HPE ProLiant DL3XX Gen11 Easy Install Rail 3 Kit (P52341-B21) is a rail kit option for mounting a compatible ProLiant server in a rack. It is identified for the DL3XX Gen11 series, providing a matching rail option for that server generation.
HPE lists a shipping weight of 3.8 kg and shipping dimensions of 13.3 × 93.5 × 8.2 cm. These are the listed shipping measurements for the kit; the source does not specify the installed rail dimensions or package contents.