North WS MDM Carbon ExtensionNorth Sails MDM extensions ensure that you spend less time rigging and maximize your time out on the water. The Carbon is our lightest MDM extension, offering a more compact and stiff material for optimum performance. The MDM extension includes 4 oversized, low friction, easy thread, corrosion resistant plastic pulleys, that line up perfectly with the sail. When combined with the low stretch Dyneema rope, an 8 to 1 pulley ratio makes high tension