Be sure to add me to your favorites list Casio 1980's ROM Pack RO-551 "WORLD SONGS" This is an early 1980's ROM pack, for many Casio keyboards of the time. It is model RO-551 "World Songs", in very good condition. I had a bunch of these at one time, but this appears to be my last one. Some of the models that can play these ROM packs are: PT-80, PT-82, PT-87, PT-40, PT-55, MT-18, MT-88, MT-800, at least some of the Casio DH digital horns, the SK-8 sampler, and the CT-810 and several other of the CT full sized keyboards. WORLD SONGS: Unterlanders Heimweh Greensleeves Die Lorelei Old Folks at Home Casio made a lot of different ROMs back in the day, and this makes a great collectible for any Casio keyboard player or collector! The following Casio keyboard models support ROM Packs (This is most likely not a complete list): Smaller Sized Keyboards: PT-40, PT-50, PT-55, PT-80, PT-82, PT-87, PT-88, PT-180, PT-280, PT-380, and PT-480. Mid-Sized Keyboards: MT-18, MT-28, MT-85, MT-86, MT-88, MT-800, and MT-820. Full Sized Keyboards: CT-800, CT-805, CT-810, and CT-840. Sampler Keyboards: SK-8, and SK-8A. Digital Horns: The Casio DH-280 and DH-800. Thanks for looking! Check out my Store!