Acorn nuts are a type of fastener whose name comes from its shape. It is a hex nut that has a closed end, dome top to prevent contact with the external thread. Acorn nuts are easily removed for maintenance to be performed, they also provide an aesthetically pleasing finished look.WARNING: This product can expose you to chemicals such as nickel, lead or chromium, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov