This does not fit the Gen 3 as I have tried. This product does not specify which caliber of the Gen 4 and so based on my experience it only fits the 9mm caliber (G17 & G19). I tried to install it on my G22 Gen 4 and it did not fit correctly.
The components included are:
1x G4 SlideComp,
4x M5 Installation set screws (side),
2x M4 installation set screws (bottom),
1x 2mm Allen wrench,
1x Glock 17 Gen 3 full size guide rod assembly.
This model is designed for Glock 17, Strike has a separate model designed for Glock 19 that can be found here:
https://www.opticsplanet.com/strike-industries-g4-slidecomp-compact.html
No, this is for full size Glocks. Provided below is a link to the model that should fit your Gen 4 Glock 23:
https://www.opticsplanet.com/strike-industries-g4-slidecomp-compact.html
It is not meant for the large caliber Glock models, so no it is not meant for the Glock model 20.
It will not be compatible unless you have a completely open muzzle design on the bottom of the holster.
No, this is not compatible with Gen 5 pistols.
You need a Gen 3 guide rod assembly.
I recommend the one by Strike Industries
https://www.opticsplanet.com/strike-industries-modular-guide-rod-for-glock-gen3.html