Factory Spec severe duty brake pads are made of a sintered bronze compound. Their exclusive high-density mix extends pad life for use in extreme conditions such as sand, mud, water and farm usage. If long life is your main concern, these brake pads are your best choice. They will last much longer than any semi-metallic or organic brake pad on the market. Manufactured by Factory Spec Included is two sets of brake pads, as pictured This is enough to replace the pads on the front calipers Made in China These sintered metal brake pads fit the following models 1990 Polaris Trail Boss 350L 2x4 1990 Polaris Trail Boss 350L 4x4 1991 Polaris Trail Boss 350L 2x4 1991 Polaris Trail Boss 350L 4x4 1992 Polaris Trail Boss 350L 2x4 1992 Polaris Trail Boss 350L 4x4 1993 Polaris 350L 2x4 1993 Polaris 350L 4x4