Moldex Bitrex Fit Testing Kit. The Approved Code of Practices supporting COSHH, CAR and CLAW stipulate that tight-fitting RPE (respiratory protective equipment) MUST be fit tested as part of the selection process. This is to ensure that the selected RPE has the potential to provide adequate protection for the wearer. There are two main reasons for doing Bitrex testing. Firstly to make sure that the respirator itself is suited for the wearer's particular face shape. Secondly to make sure that the respirator is fitted correctly to get a tight seal and ensure safety against hazards in the workplace. It is important to remember it is the suitability of the respirator that is being tested. The Moldex MOL10301 Bitrex Fit Testing Kit contains: 2 x Nebulisers.1 x Test Hood.6 x 2.5ml Ampoules Bitrex Sensitivity Solution.6 x 2.