The vacuum containers are designed to preserve the life of your coffee beans (or ground coffee).  These vacuum containers push out air that gets trapped inside the dead space in the container.   Holds up to 400g of whole bean coffee.  Air-tight. Deflects light. Adjustable height depending on the volume of beans.   The vacuum containers have a removeable mechanism on the underside of the lid.  This need to be turned clockwise to engage the vacuum mechanism. Shipping note: these containers are boxed in a thin cardboard box.  When shipped, we plastic wrap the boxes and this does distort the packaging a little.