The Lauren 608 Shell was specifically designed for the Lauren Liner. The 608 Shell creates a complete seal for the Lauren Liner at both the mouthpiece end and the shoulder end of the liner. This prohibits unwanted debris and fluid to get inside the shell and liner, thus keeping the pulsator cleaner!.The Lauren Liner locks into the 608 Shell creating an anti-twist feature to ensure proper collapsing of the liner and proper massage on the teat. Extra weight has been added to the bottom of the 608 Shell (the shoulder end) which allows the complete shell/liner combo to hang straighter and creates better balance not only while handling but also while on the milking unit. The ribs along the body of the 608 shell provide improved grip over other shells, plus it is made from a high performance engineered plastic for durability and strength!