A braking light system mounted on a road vehicle includes at least one braking light, a power source, a detecting unit, and a controlling unit. A core barrel is attached to a rotatable orienting rod. A limit module estimates a sum of a polarization voltage VP and an open circuit voltage V0 of the at least one battery at the second period based on the voltage V and current I of the at least one battery at the first period and an ohmic resistance R0 of the at least one battery. The air purifier may also have a cavity positioned along a bottom edge of a back housing to house an electrical cord provided with the air purifier. The reflection mirror is fabricated by forming a plurality of ribs at a section of the frame and inserting a soft shield plate between the ribs. Further, the process includes a step of leaving a trace of the anti-wear layer to subsist, wherein the trace of the anti-wear layer extends at least in a re-entrant zone of the Z profile of the blade.