Yamaha O2R Owner's Manual page 330

220 Installing Options
02R User's Guide
Memory Expansion Kit
The memory expansion kit (ME4M) expands the 02R automix system
memory from the standard 512K to either 1.5 MB or 2.5 MB.
Note: Take the 02R to your YAMAHA dealer or authorized service center for
installation of the ME4M kit. Doing the installation yourself invalidates the
warranty.
Wooden Side Panels
These Wooden Side Panels (W02SP) attach to either side of the 02R to give
it an attractive appearance.