Image Item No. Description  41679  Technic Rotation Joint Ball Half with 3L Liftarm Thin Catalog: Parts: Technic  41680  Technic Rotation Joint Ball Loop with Pin with Friction Catalog: Parts: Technic  x514c01  Technic Rotation Joint Ball with Arm - Pin and Hole Ends Catalog: Parts: Technic  41681  Technic Rotation Joint Socket with 3L Liftarm Thick Catalog: Parts: Technic