The fastening unit 2 includes a plurality of fasteners 24. Each fastener 24 extends through and securing together the flange through hole 113b of the panel 11 of one of the mounting units 1 and the bridge through hole 312 of one of the bridge ends 31, so that the bridge members 3 are secured to the second panel flanges 113 of the panels 11 of the mounting units 1. The number of the bridge members 3 is not limited and may be varied.

Each bridge member 3 further has two installation holes 321 formed in the bridge body 32 for installation of the power supply module 4. As shown in FIG. 10, each power supply module 4 includes an electrical busbar 41 mounted to the bridge bodies 32 of the bridge members 3 and extending in the top-bottom direction (D3). The electrical busbar 41 is used for electrically coupling server devices and has a terminal member 411 for connecting to a power supply devices (not shown).