ORIGINAL AL-KO lawn tractor mower belt tensioner pulley with eccentric Outer diameter (mm): 135 Inner diameter (mm): 42 Height (mm): 23.2 Weight: 1.3 kg For models: AL-KO BM 5001 , BM 660 , BM 870 , BM 870/II , BM 875 , BM 875/II , BM 3500