Many long range shooters use these. You use a scale to set the measure, then it will throw extremely consistant charges. I recheck the weight every time I go to a new bottle of powder. MVA pretty much copied the B&M for their current production measure. They can be found on EBAY for pretty reasonable prices. MVA also makes a Micrometer adjustable measure that can be used with these.
It's a great design, ideal for use with a drop tube in precision loading.