1,manufactured in accordance with DIN 2696 2,Lens Rings have a spherical surface Lens Rings,manufactured in accordance with DIN 2696,provide ... a high integrity,high pressure / temperature seal for specialist applications.Lens Rings have a spherical surface and are suitable for use ... overstressed.As with all metallic joints,the re-use of Lens Rings is not recommended. During assembly and use,work ...