OPF-G, DPP and OPF-PDP v2, DPP are compatible with Vortex's Defender ST and XT.
Defender ST and XT both come with a Glock MOS plate, and appropriate M3 0.5 plate to slide screws to mount the MOS compatible plate to a Glock MOS pistol Do note the plate is MOS compatible only and will not work on a Walther PDP v2, if you have a PDP v2, we offer a PDP v2 compatible DPP plate: OPF-PDP v2, DPP
In the Defender ST and XT box, there's an assortment of screws, including M4 0.7 x 11mm and M4 0.7 x 9.8mm screws. Both OPF-G, DPP and OPF-PDP v2, DPP can use the shorter M4 0.7 x 9.8mm sight to plate screws.
We suggest the screws length be measured or tested. Screws don't always hold tight tolerances, i.e. they can be longer or shorter, this isn't a Vortex issue, most screws are the same way. While there is no issues with the M4 0.7 screws being a bit shorter, it can bend the plate if the screws are too long.
If a precision measuring instrument isn't available, a visual test can still be done. Install the sight on the plate (before the plate is installed on the slide) and hand tighten the M4 0.7 x 9.8mm screws, make sure the tip of the screw doesn't protrude from the bottom of the plate. If the tip pokes out from the bottom of the plate, the tip needs to be shortened.
Do not use Leupold DPP's sight to plate screws with any sights other than Leupold's Delta Point Pro, these screws are very long (15.8mm) and they only work with DPP. Using screws longer than necessary will result in bending the plate.