Oster Blender Gasket O-Ring Rubber Seal, 3 pack. A common replacement part, this seal sits between the top of the blade and the bottom of the jar. Only one seal is needed per blender. Fits ALL Oster blenders, Osterizers and Oster Kitchen Centers. Also fits some Sunbeam models which use a metal drive pin. Measurements: 1.95â³ ID x 2.59â³ OD.