Image Item No. Description By  41681c01 (Inv)  Technic Rotation Joint Ball and (Same Color) Socket 8L Liftarm Thick with Black Loop (41679 / 41681 / 41680) Catalog: Parts: Technic 44  41679  Technic Rotation Joint Ball Half with 3L Liftarm Thin Catalog: Parts: Technic 2557  41680  Technic Rotation Joint Ball Loop with Pin with Friction Catalog: Parts: Technic 4  x514c01  Technic Rotation Joint Ball with Arm - Pin and Hole Ends Catalog: Parts: Technic 196  41681  Technic Rotation Joint Socket with 3L Liftarm Thick Catalog: Parts: Technic 1883