A roof scuttle safety railing system is provided for an existing or new roof scuttle which railing may be installed on the roof scuttle by unskilled labor without compromising the integrity of the weather seal of the roof scuttle. The portable devise includes a key body and a mechanical key. The second home position is a second preset angular position of the second camshaft relative to the crankshaft when the engine is in an OFF state. A mirror plate is connected to the hinge via a contact, and the distance between the mirror plate and the hinge is determined according to desired maximum rotation angle of the mirror plate, the optimum gap and pitch between the adjacent micromirrors.