1. COMPATIBILITY: Compatible with Standard Oster Classic Duralast Blenders that the motor base has an opening of 3 3/8' (Please see the 3rd picture) It fits models if the outside diameter of the base of the blade is 2 5/8' (Please see the 4th picture) It does NOT fit Pro, Master, or Versa models. 2. BLENDER JAR BASE REPLACEMENT: High-quality Black Blender Jar Bottom Cap Base replaces Part # 4902. The rugged plastic gear along with the gasket is perfect for keeping your goodies in the blender glass or Plastic jar where they belong. 3. SILICONE RUBBER O RING GASKET: The silicone rubber material is durable and has good elasticity and is soft enough to allow a good seal. The original gasket may break from years of wear and tear, and this spare one is an excellent replacement for it. 4. BLENDER REPLACEMENT BLADES: Premium Ice Crushing Blade that replaces original Parts # 4961. The blade is stainless steel and sharp enough to crush ice and can thoroughly blend products. The blender motor alternates the blades forward and backward, drawing food and ice down for consistently smooth g.