This replacement 182341-000-842 Silicone Rubber Sealing O-Ring Gasket is compatible with Oster Pro 1200 Blender and Newer Master Series with motor top opening of 4.25 Inches The top opening of the motor base must be 4.25" (See Picture). If it is smaller, this Gasket would not fit Please see 2nd and 3rd picture to make sure this gasket fits your blender Replaces Part # 182341-000-842. Compatible with BLSTJJ, BLSTEP, BLSTPBR, BLSMB-CGB-000, BLSMB-GTF-000, BLSMB-CBF-000, BLSMB-BBG-000, BLSTMB-CBG, BLSTMB-CBF & BLSTMB-BBG Models. Food Grade Silicone Gasket. BPA Free This replacement 182341-000-842 Silicone Rubber Sealing O-Ring Gasket is compatible with Oster Pro 1200 Series Blender and Newer Master Series with motor top opening of 4.25 Inches. Compatible with BLSTJJ, BLSTEP, BLSTPBR, BLSMB-CGB-000, BLSMB-GTF-000, BLSMB-CBF-000, BLSMB-BBG-000, BLSTMB-CBG, BLSTMB-CBF & BLSTMB-BBG. The top opening of the motor base must be 4.25" (See Picture). If it is smaller, this Gasket would not fit. Please see 2nd and 3rd picture to make sure this gasket fits your blender. Replaces Part # 182341-000-842 Models. Food Grade Silicone Gasket. BPA Free