Large chromatography columns with o-ring grooved flat flanged tops and Ace-Thred bottoms. Column extenders and 5860 heads should be mated to columns with our 6517 series clamps. All columns and extenders are supplied with either a 7855-254 (4") or 7855-260 (6") silicone o-ring. For capfe o-rings, order 7855-880 (4") or 7855-881 (6"). A wide range of bottom adapters can be used with the Ace-Thed including our 5835, 5844 and 5857 series.