Patent ID: 8166617

Claim:
A folding unit, comprising: a first arm comprising a proximal end and a distal end; a second arm comprising a proximal end and a distal end; a pin pivotally coupling the proximal end of the first arm and the proximal end of the second arm, the first arm and the second arm being configured for rotation about the pin between an open position and a closed position, wherein in the open position the distal end of the first arm and the distal end of the second arm are at opposite ends of the folding unit, and in the closed position the distal end of the first arm and the distal end of the second arm are adjacent to each other; a wheel configured and positioned for rotation around the pin; a first protrusion on the first arm; a first indentation on the second arm; wherein said first protrusion is complimentary to said first indentation, and said first protrusion fits into said first indentation on the second arm when the device is in the closed position; a first longitudinal groove on the first arm and a second longitudinal groove on the second arm, wherein said first longitudinal groove and said second longitudinal groove are on the same side of the device when the device is in the open position; a first u-shaped piece positioned at or near the end of the first longitudinal groove and sized to house the line; a second u-shaped piece positioned at or near the end of the second longitudinal groove and sized to house the line; wherein the first u-shaped piece and the second u-shaped piece are sized so that one u-shaped piece fits inside the other u-shaped piece while leaving a space for the line to move there through; a third piece positioned between the first u-shaped piece and the wheel and slidably connected to the first longitudinal groove, comprising a first curved notch that is sized to house and attach to the line; a fourth piece positioned between the second piece and the wheel and slidably connected to the second longitudinal groove, comprising a second curved notch that is sized to house and attach to the line; a second protrusion on the first arm; and a second indentation on the first arm; wherein said second protrusion is complimentary to said second indentation, and said second protrusion and said second indentation are located on opposite sides of the first arm.