They are zinc coated. I put these on on 3/27/2015 @ 137,566 mi.
Today @ 144,333 miles.
http://uploads.tapatalk-cdn.com/2016...b59e680be2.jpg
http://uploads.tapatalk-cdn.com/2016...6de345cb25.jpg
http://uploads.tapatalk-cdn.com/2016...61085e545d.jpg
Sent from my iPhone 6S using Tapatalk