Revolutionary split boot design puts an end to manifold vacuum leaks and installation headaches. I.D. Of small end is 1-1/4 inches i.D. Or large end is 1-1/2 inches . The boots fit 1971-1974 Standard Beetle 1971-1974 Karmann Ghia 1971 Bus and 1973 to 1974 Thing models. OEM NUMBER: 113-129-729BBDual Port Intake Boots Split Design With Clamps Pair