Ammeter= 52 mm , Chrome Bezel and will fit in 52mm (2") Dashboard Hole This gauge set will fit Massey Ferguson Tractors with 1/8" NPT Male Thread MF 35,50,65,135,150,165 & Industrials 20,30,31,40,50A,70,202,204, 2500 TE20, TEA20, TO20, TO30, Massey Harris 22, 33, 44, 55, 333, 444, 555.Thank You for your visit .