Polaroid back M80 for Mamiya RB67

just got a back for my RB67, it look perfect and cheap $39, then my brand new for testing fuji FP-100c and my polaroid 664 wouldn't feet inside. A quick research using the name M80 (something was not part of item description before purchase) tells me that only takes the type 80's old polaroid pack films, discontinued, and only found in the second hand market. I found things like this online:

"Up for sale are 40 packs of unopened Polaroid Black and White, Land Pack Film Type 87. This film is outdated by 32 years as it was to be used before 1977. Please E-mail any questions."

Is anyone familiar with this type of polaroid back that takes 2 1/4 by 2 1/4 or something like that? Do I send it back or try to find used film online?

I am sending it back, why do people sell things that need parts that have been discontinued? blame my ignorance I guess.