I was really surprised at the quality and power of this product. The glass container is thick and heavy, fits firmly on the base. The rubber top also fits firmly so you don't need to keep your hand on it when in use on full speed. The vent may open a little If you fill it close to the top. I always start with the pulse button to make sure it is not too full. I bought this to make homemade peanut butter, smoothies and the like. It's also perfect for bread and cookie doughs. I am completely happy with this product and recommend it to everyone.