13mm WEST MATTE FLIP CAP VIAL SEALS For serum vials with a 7mm hole opening and 13mm outer rim diameter. The new West Pharma "Matte" finish resists scratching during transit and handling. No words or logos on the plastic button - complies with new USP Chapter 1 regulations: USP General Chapter <1> Injections, Section on Labeling on Ferrules and Cap Overseals