Professional Choice-The constant pressure tamping machine has been tested and uses a constant force of about 30 pounds to tamp powder during extraction, which helps to improve the flavor and stability of espresso. Model-This product is suitable for 51mm Please note that 30 pounds of pressure requires professional instruments to measure, and cannot be measured by scales, etc. Tips-It is recommended to use it with a distributor to evenly distribute the powder bed, effectively reduce the channel effect, and improve the stability of extracted espresso.