For years I've used a stethoscope w/ an antimicrobial cover. For this brand stethoscope (maybe others, too), the traditional inner diaphragm is removed before the cover is placed, then the cover becomes the diaphragm. I've tried several different stethoscopes through the years, including Littmann, ADScope, DRG, WelchAllyn, and TrimLine, and the acoustics of my stethoscope w/ the antimicrobial cover are second to none -- crucial in my job as a peds cardiac nurse, where clearly differentiating heart and lung sounds is required. As for where to purchase them, many of the catalog and on-line uniform retailers sell the SafeSeal brand covers. I use mine longer than the recommended 1 week; they clean nicely w/ alcohol and hold up well to heavy use.