The Roland PSB-230EU Is a 9 Volt and 2000mA power supply with a 1.3mm inside bore and 5mm outside bore. The polarity is inside negative. The PSB-230EU is also the succeeding model from the PSB-1U power supply which is commonly used on Roland / Boss products. Note please check your unit or the suitable products list before purchasing this as a replacement for any Roland or Boss product.