The JMK Instruments are the instruments that Johnny Mushroom and the Kingdoms use.
The JMK Instruments are the instruments that Mario, Luigi, and the other members use in their band Johnny Mushroom and the Kingdoms. They are mainly comprised of guitars, a keyboard, a drum, etc.
After the episodes "Who is Scott Masterson?" and "Guess who's not invited...again," they have no instruments and appear as
an Acapella group.
In "JMK FOREVER," they return to instruments.