A fixing device for securing an antenna to a front panel of a computer enclosure, includes a main body, two fixing arms extending from opposite ends of the main body, and two locking arms extending from the main body and perpendicular to the fixing arms. A light path system of a laser beam machine comprises a light path duct 10 having a U-shaped cross-section with the upper end opened, and a light path 12 into which clean air is fed. Furthermore, the internal member is adaptable to seat a heat sink. The floor strip has a tab portion on a surface that engages a channel on a floor tile or a reducer.