What is da style finish nail?

DA refers to the angle the nails are collated. There are two types of 15 gauge finish nails, DA or FN. DA nails are collated at 34/35 degrees and FN nails are collated at 24/25 degrees. The type of nail you need is determined by the nail gun you own or are planning to use. Bostitch and Grizzly are the two primary manufacturers of FN nail guns, while most other nail gun manufacturers use the DA type nail, although Bostitch also manufactures a DA style finish nailer as well.