Harken® Classic blocks have stood the test of time. For over 35 years, these strong, light and exceptionally free-rolling blocks have provided both racers and cruisers dependably correct hardware for every trimming task. Ball Bearings: Carbon-black Delrin® ball bearings roll on flat races for exceptionally free-running blocks. Stainless Steel Sideplates: High-strength stainless steel sideplates distribute load evenly. UV Protection: Black ball bearings and sideplates are US-protected to provide maximum durability. Three-way Head: Three-way head locks shackle in front or side positions, or swivels freely to keep line from twisting.