35 mm films are pulled, this means all of the film is extracted from its roll. This can be done manually or by using a small machine that essentially uses tape to pull the film leader and all of the film out of the cassette. This small machine may be integrated into the film processor. If so, rolls are inserted inside a chamber, slot side towards the inside of the machine pointing downwards at an angle of 45°, the chamber is closed and the film inside the rolls is pulled into the processing mechanism. In cases when the end of the film cannot be removed or if the film is damaged, the film can be removed using a dark bag or a dark box. Before processing, a twin check number (a pair of stickers with a unique number) is manually put onto the film and the matching number onto the film processing envelope, so that after processing this film can be easily identified to the customers envelope. Films are spliced on the leader cards one or two at a time, to do this the end of the film is cut square, special chemical-resistant tape is used to attach the film to the leader card. The leader cards are then inserted into the film processor mechanism and are fed through the machine using sprockets in the card. The film goes through a developer, bleach, fix and stabilizer, then through a dryer. After the film is processed it is cut from the leader card and reunited with the processing envelope containing the customer details, and then from here the film goes forward for printing. Alternatively the film may be used immediately to expose silver halide photographic paper, shining a bright light through the film and into the paper using lenses for optical enlarging, which is then processed like film in a separate mechanism. Or the film may be digitally scanned using a CCD image sensor, corrected using software, and sent to a digital silver halide printer.