Water inlet Radiator Filler Neck. 1 x Filler Neck. Breather thread:NPT1/16. High Standard 6061 Aluminum. Made of material, and practical to use. Size approx: ID 42mm, OD 56mm, H 25mm. The real color of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness.