For pre-2004 models, this is an alternative twin gas cylinder connection system which uses your existing regulators. it is designed for the low pressure side of your gas system after your regulators. the two supply inlets are controlled by a two-way tap and can use either type of LP gas - one side can be Propane, the other side Butane. Switch-2 makes changeover easy and allows the empty cylinder to be removed without switching off the supply. It is supplied with 3 hose clips and fitted with a mounting bracket.