What is this?
Pushing and pulling film means changing film's exposure by changing the amount of time that your film is processed; pushing is more development time, pulling is less, and the values refer to the 'stop' of exposure change.
+1 makes 200 ISO into 400 ISO, -2 makes 800 ISO into 200 ISO, etc. This should only be used if the film that we'll be processing has been intentionally shot for 'push processing'
$2 per push/pull roll