The DAA Dropper Assembly is needed for shooters who wish to set up a second tool-head in the same caliber, and wish to quickly transition from 9mm to .38 Super, for example, or from one 9mm bullet to another. A change is needed to the collator parts, and if a second tool-head is to be used on the progressive reloader, it is quicker and easier to leave an adjusted Mr.Bulletfeeder dropper on each tool-head. This allows for quick swapovers, without the need to calibrate or adjust the dropper. Note that in most cases you will need to purchase an additional Powder Funnel for your second tool-head’s powder measure, as the Double Alpha expanding Powder Funnel is required for troublefree reloading.