This Sea-Dog Line Trailer Plug Adapter, 7 Round to 4 Flat, is used to convert a 7-way round trailer connector on a towing vehicle to a 4-way flat connector, which is commonly used on smaller trailers.
"Warning - this product contains chemicals, including Phthalates [B], known to the State of California to cause cancer or other reproductive harm - For more info go to www.P65Warnings.ca.gov"
www.P65Warnings.ca.gov