BOSS BX-4 4-channel mixer. It has been cleaned simply. Operation has been confirmed with both batteries and an adapter. The adapter is not included. There are scratches and dirt, but there are no problems with use. Instant purchase is OK. Thank you. --- 4-channel line/mic mixer with gain and volume adjustment. - Model: BOSS BX-4 - Number of channels: 4 channels - Functions: Line/mic input, gain adjustment, volume adjustment - Power supply: Compatible with 9V batteries - Master volume: Yes Thank you for viewing.