3M sensitivity solution ft-31, bitter, 1 bottle used to test the sensitivity of the respirator wearer to a bitter solution. It is used with the 3M qualitative fit test apparatus ft-30. Test kits and accessories designed to help your organization meet osha fit testing requirements for respirators. The products can be used to check face-to-respirator seal on any particulate respirator or gas/vapor respirator with a particulate prefilter.