Eartune Fidelity tips are made based on the design of one specific IEM. Eartune Fidelity Mini tips are made based on user specified Core Diameter (CD) and Core Length (CL). While Eartune Fidelity tips are designed to work with the intended IEM 100%, Eartune Fidelity Mini tips may or may not work with the intended IEM - compatibility will depend on the weight, shape and wearing style of the IEM. Eartune Fidelity tips are only compatible with one IEM they are designed for. Eartune Fidelity Mini tips can be compatible with any IEM that share its CD and CL specification.