A guard for headgear, the guard comprising a transparent guard member 1 and releasable attachment means in the form of a spring clip 3 to attach the guard to extend downwardly from the headgear, wherein the guard member 1 is pivotable about an edge, such as a peak, of the headgear. A light source lamp unit includes a light source lamp having a light emitting section in which discharging emission is performed between electrodes, an elliptic reflector to emit a luminous flux radiated from the light source lamp in a certain uniform direction, and a secondary reflecting mirror provided on the opposite side of the light source lamp opposite from the elliptic reflector. The CP flip-flop receives a clock signal, delays the clock signal for a predetermined time period, and detects the delay time period from the clock signal. The bicomponent fiber provided in this invention is biodegradable, environmentally benign and with excellent bonding performance to polylactic acid fibers, chemical fibers and cellulose fibers. The input logic unit is responsive at least in part to each of the output full signals, and further operative to cause a selected packet received via the associated receive port to be dropped if the associated receive port is currently saturated and the output full signals indicate that a destination transmit port associated with the selected packet is currently congested.