This instrument is the chromatic half of the PP019 alto metallophone. They are designed to sit together in order to create an entirely chromatic instrument.
Do see our full listing for the PP019, (look at the 'recommended accessory' portion of this web listing) for more information.
The Perfect Pitch range of instruments are produced here in the UK by Percussion Plus. They are well engineered, have precise tuning and lovely overall build quality and last well in schools.