Used to adjust weight percentages inside the car by the driver with the turn of a knob! 4" OD and 2 3/8" ID jacking cup.See additional parts in my store, Used Race Parts Supply. The item "Internally adjustable screw jack weight jacker Late Model Dirt Car" is in sale since Thursday, April 25, 2019. This item is in the category "eBay Motors\Parts & Accessories\Car & Truck Parts\Other Parts". The seller is "mart686" and is located in Asheville, North Carolina. This item can be shipped to United States, Canada, Australia, Japan, China, South Korea, Indonesia, Taiwan, Thailand, Hong Kong, Bahamas, Israel, Mexico, New Zealand, Philippines, Singapore, Saudi arabia, United arab emirates, Qatar, Kuwait, Bahrain, Malaysia, Aruba, Dominica, Grenada, Saint kitts and nevis, Saint lucia, Montserrat, Turks and caicos islands, Barbados, Bangladesh, Bermuda, Brunei darussalam, Bolivia, Egypt, French guiana, Guadeloupe, Jordan, Cambodia, Cayman islands, Sri lanka, Macao, Martinique, Maldives, Nicaragua, Oman, Pakistan, Paraguay, Reunion, Uruguay.