Barton BPI-20 Bulkhead Pipe Gland Reducer 20mm f/BPG-50 [BPI-20]BPI 20 Bulkhead Pipe Gland Reducer 20mm for BPG 50 This adaptor enables smaller pipes to be used in conjunction with the BPG 50 Pipe Gland. This will accept pipes between 18. 5 and 20mm. These glands give a water and vapor proof seal between bulkheads. They are flexible and will accommodate curved surfaces and pipe entry at an angle. They are easy to fit and fully serviceable in situ.