Film or paper cassette

A two part clamshell web cassette is provided with a central recess for receiving a web roll core. The core and cassette half shells have mating surfaces which form a labyrinth light seal when the cassette is closed and which prevent rotation of the core during handling of the cassette to provide a core brake. Surfaces on the cassette parts clamp the web rail of a partially dispensed web roll when the cassette is closed. The core brake and web clamping surfaces facilitate transport of the cassette without loss of intra-roll web tension. The cassette is provided with a latch for retaining the cassette half shells in a closed light sealed condition. A frangible covering over a latch release means indicates when broken that the cassette may have been opened prematurely. The cassette further includes a web end retaining means which retains the web end portion to the underlying convolution. The cassette further includes an orientation of light to be identically molded and then rotated 180 degrees during assembly to cause the light blocking surfaces to mate.