The SI airbrush is single action but also internal mix which keeps operation simple but allows for better detail than external mix models.  The SI single action allows the user to achieve fine lines down to 1/32 inch and wider patterns of up to 1-1/2 inches.  The best uses are those requiring more basic spraying like solid coats, uniform lines or stencil work.  Clean up is as simple as spraying your paint cleaner though the airbrush.  The SI is used for many applications including hobby, craft, chip and ding repair, taxidermy, ceramics, cake decorating, tanning, tattoos, etc.  The SI airbrush is made in the US.