The D9 is the same as the D10, but it comes as a kit. Note the peanut type steam whistle that reminds one of the old weighted lever whistles. This is also present on the D5, D6, D8, D10, D106, D455 and Spreewald loco kit, also known as Lucas or the D001. I have owned this engine from new, and it runs silky smooth, though it isnt as powerful as I first thought it should be.