N.Y. Comp. Codes R. & Regs. tit. 15 § 69.3
The caution arm shall be made of any durable material. That part of the swing arm that is attached to the vehicle itself shall be 7 3/16 inches in height and, when extended outward and to the side of the vehicle, shall extend to a length of 18 inches and flared to a height of 18 inches. Located at the upper and lower corners of the 18-inch side will be flashing yellow lights visible from the front and from the rear. These lights shall be four inches in diameter and shall flash simultaneously. The background of the sign shall be painted yellow and shall be reflective. The lettering shall be painted black. In the middle, in letters five inches in height, shall be painted the word "SLOW"; just above the word "SLOW" shall be painted in two-inch letters the word "CHILDREN"; just below the word "SLOW" shall be printed in two-inch letters the word "CROSSING". The sign shall be lettered and painted on both sides so that it will be visible from both the front and rear.
N.Y. Comp. Codes R. & Regs. Tit. 15 § 69.3