This 5-pack of stop light switches fits Mack and Volvo applications. Each switch is a normally open design that closes at 4 psi, with a 1/8 in.-27 NPT thread and a protective coating. Mounted near the brake pedal, it closes the circuit when the pedal is depressed to trigger the brake lights.Interchanges:Mack 1MR24131MR2413A1MR33591MR3359AP11MR3359P125161904Freightliner FSC1749-1121This unit is sold in packs of 5.FeaturesPack of 5 stop light switchesNormally open at 0 psi, closes at 4 psi1/8 in.-27 National Pipe ThreadProtective coatingFits Mack and Volvo applicationsTech SpecsType: Stop Light SwitchOperation: Normally open at 0 psig, closes at 4 psigThread: 1/8 in.-27 NPTFinish: CoatedDimensions (H x W x L): 1 in. x 3.25 in. x 3.25 in.Pack quantity: 5 piecesAdditional InformationApplication: Mack and Volvo.