A preform configured to form a container by stretch blow molding. A finish portion is at a first end of the preform, and is a container finish. A tip portion is at a second end of the preform opposite to the first end, and is configured to form a container base and a container heel. The shoulder portion is adjacent to the finish portion and is between the finish portion and the tip portion. The shoulder portion is configured to form a container shoulder. The body portion is between the shoulder portion and the tip portion, and is configured to form a container body. The outer surface includes a first flat portion and a second flat portion at the tip portion. The first flat portion extends at a first angle and the second flat portion extends at a second angle that is different than the first angle.