This is the Yamaha KPA6 mains adaptor - for use with Yamaha keyboards such as the DGX range and some of the mid range PSR range keyboards, including the PSR350, PSR450, PSR620, PSR740 etc.

It is also suitable for the DD range of drum machines, such as the DD65 DD50 DD55 etc.

This product is sometimes referred to as the Yamaha KPA-6 or KPA 6