This is a Yamaha "Sho-Key" (shoulder keyboard). All keys produce sound, and I have confirmed that the other functions are also working properly. There are no manuals or accessories. Everything included is shown in the photos. The power adapter (DC9-12V) is not included. Operation has been confirmed using dry cell batteries. The sponge-like material inside the battery cover has been removed due to hydrolysis. The battery terminals are free of corrosion and there are no issues with electrical conductivity. Considering it's almost 40 years old, it has been well-preserved and is in good condition. There are no noticeable scratches, but there may be minor scratches and some yellowing on the white keys. Please check the photos. If you need any additional photos, please let me know and I will upload them.