Every vehicle which is used to vend frozen desserts to pedestrians on public highways or sidewalks shall be equipped with a caution arm on the left side which meets the standards described in section 69.3 of this Part. The caution arm shall be extended whenever the vehicle is stopped on a public highway to vend frozen desserts. The caution arm shall be retracted whenever the vehicle is in motion or is not being used to vend frozen desserts.
N.Y. Comp. Codes R. & Regs. Tit. 15 § 69.2