Came in from Other World Computing as a matched pair. 10 screws to remove using a Phillips #00 screwdriver. Be very careful with the screws. 3 of them are longer and they need to go into those matching holes on reassembly. Had a slight problem with the machine not recognizing the full 8 gigabytes. So, had to re-open the case.
Moral: Don’t close up the case until the machine sees the full amount of memory. I needed to reseat the cards.
Technical support via email from OWC is amazingly quick.
With 8 gigabytes and an SSD, the machines, a little 13 inch MacBook Pro, flies.