Sievert 8716 Neck and Valve Assembly for direct connection onto the Primus 2000 cylinder giving precise flame control. Back pressure valve to reduce the risk of flare up, it will accept burners of M8 x 0.75 thread from the Sievert Burner range 8725, 8719, 8720, 8842. Compare prices from: Sievert in Hardware & Ironmongery