Single-Hook Anchor Chain Tensioner for 5/16' Chain These fittings will securely tension and hold the anchor in the bow roller channel.  They will free up use of the bow cleat and prepare the anchor for sea condition assuring you peace of mind.  This fitting is not designed to take the strain of the rode of a boat at anchor.  'Single Hook' style has overall length of 12', the threaded hook has 1-1/2' of adjustment for ease of installation.