This insulator set fits Mack universal applications and comes as a pack of two. Each piece acts as a non-conductive buffer that cuts down on heat transfer, vibration, and noise between the components it sits between. It installs wherever the original insulating piece is called for on Mack platforms.Interchanges:Mack 20QL231P10Mack 20QL252P2FMT-4907This unit is sold in packs of 2.FeaturesPack of 2 insulatorsFitment: All Mack UniversalTech SpecsFitment: All Mack Universal