Due to the overall length of the TFX® and TFO® series sights, they will not be compatible to be used in conjunction with a red dot. There is simply not enough surface area on the slide to mount both a red dot and our TFX® and TFO® series sights.
However, TRUGLO does offer our Tritium Pro sights that are Glock MOS compatible that will provide a lower 1/3rd co-witness. Below will be a link where you can find the Tritium Pro Glock MOS sights on our website. The sight part number for the Glock Model 19 will be TG231G1MW.