Big Horn 11490- 4" Spherical 360 degree swivel Ball Joint. Big Horn offers 4 inch Swivel Ball Joint that provides flexibility in duct layout and features a swivel design that allows up to 20 Degree direction change. This ball joint features a 4-inch port that connects to any dust collection system and has a tough plastic construction for reliable use over a long period of time. This swivel ball joint connects to a standard 4 inch dust collection hose.