a bottom plate, wherein the bottom plate is provided with a connecting position and a mounting screw for connecting the bottom plate to a photographic device using the mounting screw;

a grip, a mounting slot is provided in the grip, a positioning pin is provided in the mounting slot; and

an expansion assembly connected to the bottom plate, the expansion assembly and the mounting screw extending from the bottom plate toward a same direction,

wherein the bottom plate is connected to a bottom side of the expansion assembly,

wherein the expansion assembly comprises a hard disk mounting plate,

wherein the hard disk mounting plate comprises a hard disk interface, and an external interface for connecting to the photographic device mounted on the connecting position, the external interface adapted to connect to a memory card slot of the photographic device,

wherein the expansion assembly is configured to detachably receive a hard disk in the expansion assembly, and the hard disk is connected to the hard disk interface,

wherein one side of the grip is provided with a first cooling hole penetrating into the mounting slot, and one side of the hard disk mounting plate corresponding to the first cooling hole is provided with a first thermally conductive rubber pad,

wherein the other side of the grip is detachably provided with a cooling fin for covering the mounting slot, a protrusion hole is formed between a side edge of the cooling fin and the other side of the grip, and the external interface protrudes out of the grip through the protrusion hole, and

wherein the cooling fin is provided with a second cooling hole, and one side of the hard disk corresponding to the cooling fin is provided with a second thermally conductive rubber pad.