TSIâ€™s PORTACOUNT© Plus enables easy, reliable fit testing for tight-fitting respirators. Utilizing convenient FitPlusâ„¢ quantitative fit testing software, PORTACOUNT makes a direct measurement of respirator fit factors. There are no error-inducing assumptions made to calculate â€œequivalentâ€ fit factors. Available adapters allow fit testing with employeeâ€™s own mask. TSI, Inc., Shoreview, MN.