A rolling d-ring provides a climber with greater mobility than a fixed d-ring saddle by creating a pivot point at the waist. Since the mid 80's this general design feature has been a leading seller within the arborist industry. Since its inception, the only complaint from users has regarded premature wear to the supporting saddle strap from an small steel roller. Innovative climber and ArborMaster champion Paul Sisson from Washington state developed a most excellent idea, which is now available to all climbers who desire a smoother ride and greater life for their harness. The HDP Roller is made of High Density Polyethylene and milled perfectly to fit the Petzl William carabiner. The roller is 2" long and 1 9/16" in diameter and works great with all rolling-d type saddles. One or more may be used at a time depending upon technique of user. Early tests show no visible wear to either the roller, carabiner or saddle support strap in 4 months of heavy use!