Review on Oster BLSTTS-CB2-000 Pro Blender: Texture Select Settings, 2 Blend-N-Go Cups, 64oz Tritan Jar - Brushed Nickel by Sarah Moore

DOES NOT LEAK if you follow the instructions. The black o-ring fits over the black plastic base and is used with the pitcher. The gray gasket is matched to the gray plastic base and is used with cups. The seal is installed on the TOP of the blade disc, not underneath. The gray seal has ribs that press into the base and hold the blade in place when you turn the mug upside down. Works perfectly. Great design.