Flexible package fitments for use with detachable dispensing systems are provided. Pouring spout fitments configured to be attached to the inner surface of flexible containers are also provided. The detachable dispensing systems and pouring spout fitments include a hollow rigid member and an extendible spout disposed within and at least partially attached to the hollow rigid member and selectively positionable between a recessed position and, alternatively, an extended position, in which the extendible spout is configure to dispense a pourable material from the container through a distal opening when the fitment is attached to a flexible package. Material containers are also provided that include the fitments described herein.