This Bearing Replaces Arctic Cat OEM Part numbers 3604-033 and/or 1604-847. It fits most Arctic Cat snowmobile idler pulley wheels. The bearing has an inner diameter of 20mm an outer diameter of 42mm and a width of 12mm (20x42x12MM). Specifications: Exceeds OEM Specifications - Extreme Close Contact NBR Seals - Proprietary Synthetic Off-Road Water and Rustproof Grease - High Precision Bearings