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There are four general types of brake pads for cars and trucks:

Semimetallic: This formula, containing about 30 to 65 percent metal, typically includes chopped steel wool or wire, iron powder, copper or graphite mixed with inorganic fillers, and friction modifiers that bond all the ingredients together. These pads are more durable and have excellent heat transfer, but also wear down rotors faster, can be noisy, and may not perform optimally at low temperatures.

Nonasbestos organic: Sometimes listed as organic or NAO, this type of pad is made from fibers, such as glass, rubber, carbon, and Kevlar, with filler materials and high-temperature resins. These pads are softer and create less noise, but they wear faster and create more dust.

Low-metallic NAO: These are made from an organic formula mixed with small amounts (10 to 30 percent) of copper or steel to help with heat transfer and provide better braking. With the added metal, there is more brake dust and they may be slightly noisier.

Ceramic: These are composed of ceramic fibers, nonferrous filler materials, bonding agents, and possibly small amounts of metal. Lighter in color and more expensive than other brake pads, ceramic pads are cleaner and quieter, and offer excellent braking characteristics without wearing down the rotors.