Check the listing for details. RAM Mount 4" Max Width Clamp Base with 1.5" Diameter Ball RAM-247U-4. Condition: New. Listed at 41.49 USD. Manufacturer DescriptionOVERVIEW: The RAM-247U-4 is a clamp base with 1.5" rubber ball that will connect to rails up to 4" maximum in width.HARDWARE INCLUDED: (2) 5/16"-18 x 3" Machine Screws, (2) 5/16"-18 Nylock NutsCLAMP RANGE: 4" max widthBALL/SOCKET SIZE: C Size (1.5")WEIGHT CAPACITY: 4 lbsMATERIALS: Marine-grade aluminumPACKAGING TYPE: Poly BagWEIGHT: 1.17 lbs.FeaturesClamping base ideal for square posts up to 4" in width; adjustable and easily removableIncluded C size 1.5" RAM® rubber ball allows for connection to any C size RAM® double socket arm; ball and socket technology allows for near-infinite adjustabilityMade of powder-coated, marine-grade aluminum for durability and reliability in the most demanding environmentsBacked by a lifetime warranty