This is the only fitting that should be used to connect the metric poly pipe to the pump and the underside of the bore cap.   The male BSP brass thread will ensure that everything stays put exactly as it should.   The whole weight of your submersible bore pump should hang on the metric poly pipe and so, the threads on the fittings are absolutely critical and brass threads are perfect for the task.   This fitting fits 50mm metric poly pipe and all 40mm outlet threaded pumps.