Polaroid 636 Repair Manual page 21

5. On the other hand, a 600 film pack cannot be inserted into an SX-70 style camera since the
tabs on the pack are held back by the older style pack springs.
6. The battery in the 600 film pack has a higher capacity than the conventional SX-70 battery.
It provides power for the shutter solenoid, the motor and for the built-in electronic flash.
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