This is a complete kit with all rollers needed for the M681 with 4 trays, very well packed and organized. It has instruction booklets for each type of roller, with pictures to show how to replace each one. There are tools included that help with removing the old rollers and properly seating the new ones. I installed two of these in the past week, the second one took less than 1/2 hour to complete.
I ordered the transfer kit because my printer gave me a message to order it, but the "kit" that I bought had about 10 parts that my machine did not have. there should be a way to input the serial number and get ONLY the parts needed for that machine.