The word from the manufacturer is:The manual blender of the jug mixes the chocolate powder and milk in a smooth way producing an uncongested froth without too much squirting. The cleverly devised manual blender consists of a propeller attached to a spiral rod making it a fun-to-use tool and ensuring the best mixed chocolate milk - the "sinful temptation" par exellence! The jug turns into a multi-purpose object as soon as the lid is removed, carrying any liquid from milk to lemonade to water. http://www.bodumusa.com/shop/line.asp?MD=1&GID=83&LID=553&CHK=&SLT=&mscssid=HFD3VT08M35C9JB2HM0AMNMUP64A5F76
updated by @teresa: 04/10/15 11:55:44