A preform configured to form a container by stretch blow molding. A finish portion of the preform is at a first end of the preform. The finish portion is a container finish of the container. A support flange is at the finish portion. A tip portion is at a second end of the preform opposite to the first end and is configured to form a container base. A neck portion is adjacent to the support flange, and is configured to form a neck portion. An external stretch radius is at an outer surface of the neck portion. An internal stretch radius is at an inner surface of the neck portion. A first distance is between the internal stretch radius and the external stretch radius and is equal to, or greater than, four times a second distance between the external stretch radius and the support flange.

A preform configured to form a container by stretch blow molding. A finish portion of the preform is at a first end of the preform. The finish portion is a container finish of the container A support flange is at the finish portion. A tip portion is at a second end of the preform opposite to the first end and is configured to form a container base. A neck portion is adjacent to the support flange, and is configured to form a neck portion. An external stretch radius is at an outer surface of the neck portion. An internal stretch radius is at an inner surface of the neck portion. A first distance is between the internal stretch radius and the external stretch radius and is equal to, or greater than, four times a second distance between the external stretch radius and the support flange.