The Ninja DUO blender has a great build quality. Although most of the blender, including the transmission gear, is made from cheap-feeling plastic, it still seems pretty solid. The main blending jar also has sturdy metal blades fixed directly to the bottom of the jar. While the blades can’t be removed for easier cleaning by hand, the combined jar and blade assembly can be washed is top-rack dishwasher safe.
On the downside, the main container doesn’t seem to be shatter-proof and it could crack if you drop it. Water and other liquid can also get stuck in places such as inside the main jar’s handle or inside the vacuum seal area of both the main and additional jar, which is a little annoying.