All aluminum arm construction. Total arm length is 9.5". Dual ball and socket joints provide multiple points of articulation. Locking elbow joint allows for additional positioning options and accommodates the iGoSmart-Pro Suction Cup Pad Mount. The center of at the arm position turns up to 180 degrees and the end ball units turn 360 degrees allowing for perfect viewing and adjustment angles. 20mm ball not included. This is not compatible with 17mm ball mounts. This is compatible with 20-21mm ball mounts which are separately and not included in this package. For more information on how this arm works please see our Youtube page and do a search for iGoSmart-Pro on YouTube. We also have a longer 15" version of this arm available which comes with 1/4"-20 male ball ends on each side. Search under our products to see longer arm version. Recently Amazon fulfillment has been taking a long time to restock if you need the item in a hurry you can order directly from our website as we have product in stock on our website and don't have fulfillment waiting issues.