Apparatus for testing, measuring, indicating, recording and/or analysing breath for alcohol; control apparatus for or responsive to the aforesaid apparatus; apparatus for analysing alcohol in breath fluids; engine cut-off devices; engine cut-off switch; sensors for use in the control of engines; sensors for use in the control of motors; electronic controls for motors; remote controls for motors; electronic control sensors for motors; engine cut-off devices controlled by breath alcohol levels or the absence thereof; engine cut-off switch controlled by breath alcohol levels or the absence thereof; sensors for use in the control of engines controlled by breath alcohol levels or the absence thereof; sensors for use in the control of motors controlled by breath alcohol levels or the absence thereof; electronic controls for motors controlled by breath alcohol levels or the absence thereof; remote controls for motors controlled by breath alcohol levels or the absence thereof; electronic control sensors for motors controlled by breath alcohol levels or the absence thereof; immobilisers for vehicles controlled by breath alcohol levels or the absence thereof; breathalysers for use in immobilising vehicles based on breath alcohol levels or the absence thereof; vehicle immobilisers controlled by breath alcohol levels or the absence thereof; vehicle immobilising breathalysers controlled by breath alcohol levels or the absence thereof; vehicle engine immobilising mechanisms based on breath activation; breathalysers; parts and fittings therefor.