And yes, you want the smaller one. The 4x5 film is discontinued but still available some places. But even before it was discontinued it was three times the price of the smaller film. The 3.25x4.25 is pretty close to the size of 4x5. Be aware the image isn't centered on the 4x5 ground glass. There's a thread in Image Sharing here for Polaroids and "Fujiroids" and in that thread I asked about the mask for the 4x5 ground glass since my holder didn't come with one and most don't seem to. Others replied with links to a pdf template where you can print out your own.