A grooved rail core piece including a core piece intersection area formed by intersecting grooves as an overflow area. The first lens unit is configured for correcting chromatic aberration of the projection lens. The spaced holes of the first surface have diameters that are greater than 2 mm and less than 8 mm. Button motion may also be used to cause retraction of latches mounted on the battery housing. The system includes a rechargeable battery of a vehicle, an electric traction motor of the vehicle, and an external vehicle interface configured to rotate the shaft of the electric traction motor using mechanical power while the vehicle is stationary.