California Code, Vehicle Code - VEH § 26708.2

(a) The devices shall be held in place by means allowing ready removal from the window area, such as a frame, a rigid material with temporary fasteners, or a flexible roller shade.

(b) Devices utilizing transparent material shall be green, gray, or a neutral smoke in color and shall have a luminous transmittance of not less than 35 percent.

(c) Devices utilizing nontransparent louvers or other alternating patterns of opaque and open sections shall have an essentially uniform pattern over the entire surface, except for framing and supports. At least 35 percent of the device area shall be open and no individual louver or opaque section shall have a projected vertical dimension exceeding 3/16 inch.

(d) The devices shall not have a reflective quality exceeding 35 percent on either the inner or outer surface.