NABP recognizes the need for a heavy-duty security/bullet resistant steel door. All of our SDR series doors have a structural steel internal framework and minimum 10 gage door skins. These high performance blast resistant doors are available in all U.L. and N.I.J. performance levels. We have frequently manufactured the SDR in .50 caliber performance. As with all of our doors the SDR can be outfitted with any viewlite.