Tuna knobs are control knobs that stick to any touchscreen and let you control DJ and music making apps like you would with dedicated music hardware. Tuna Knobs are designed to give you the tactile precision you need when making music, while giving you the versatility of mobile applications. Tuna Knobs are basically a stylus in the shape of knob, with a small axis in the middle and a suction cup on the bottom. Made to control (music) apps with virtual knobs on every touchscreen device.