Our Bottle Caps offer ease of use and are economical. We provide three holes in each cap insert that have no stops. With two of the holes, you simply push your tubing through. The third hole accepts any male luer or our A-626 tapered plug (except the A-610 and A-610B). The A-610 and A-610B bottle caps have a 3/16" third hole configuration for use with a Waters® system. If needed, this hole takes an A-628 plug.