Complete Coat Stoppers are completely coated with a fluorinated polymer that has barrier properties similar to PTFE. The fluorinated polymer coating is the only material that comes in contact with the sample. As a result, chemical reactions due to unwanted interference with the rubber itself are virtually eliminated. These stoppers are manufactured in a silicone-free environment. The specialized manufacturing process produces extremely low levels of visible and subvisible particles. These stoppers provide users the greatest level of confidence in avoiding interference with samples.