A specific filter basket is one that is designed and manufactured precisely for a particular model or brand of coffee machine. Coffee machine manufacturers do not use a uniform standard for the dimensions and shape of filter baskets; therefore, they may differ in diameter, depth, or the shape of the upper rim. These differences ensure that the filter basket correctly fits into the portafilter and subsequently seals correctly in the group head of the coffee machine. Using an incompatible filter basket can lead to water flowing around the ground coffee instead of through it, which negatively affects the extraction process and the resulting taste of the beverage.