Allows the boater to dock his or her boat in the slip to either the Port or Starboard side only. 2 SwiftKnots included: one SwiftKnot is used on the Port or Starboard Bow line, one SwiftKnot is used on the Port or Starboard Stern line. Also makes fender adjustments quick and easy. Mini SwiftKnot: For boats 27’: 3/8" Dock Line, boats 27'- 35': 1/2" Dock Line; 3/8"-1/2" Fender Line