SEMI-METALLIC
Semi-metallic brake pads are made with portions of metallic fibers in the brake pad compound. High quality semi-metallic pads contain fine metallic fibers while lower, cheaper quality pads have larger, more coarse portions of metal.

Pros:

Effective grip even when cold ? great for colder climates and driving habits that require short trips
Less expensive than ceramic pads
Typically easier on rotors than ceramic pads