Korkers are strapped on boot bottoms that have tungsten carbide cleats in their bottoms. The cleats are threaded and replaceable. Korkers come in various sizes and easily fit over your boots and are buckled on. They provide good traction, even when walking on slick mossy rocks. Korkers are a necessity for fishermen who fish on jetties and on rocky shores.
New Korkers are on the left. Bob's well used Korkers are on the right.
See: Korkers available at Amazon.com
Two examples of where you need Korkers are shown below.
You should use Korkers when fishing on Jetties, such as the north jetty at Island Beach State Park, New Jersey.
Photo by Shore Catch Guide Service.
You should use Korkers when fishing rocky places such as are found at Browns, Montauk.
Some fishermen wrap duct tape over the Korkers to assure that they won't come off as they hop between rocks.
See Korkers on: Striped Bass Fishing Gear