These TruGlo Brite-Site TFX Sights are not compatible with the Glock 31. You would need model MPN:TG-TG13GL5A which can be found by using the link below:
https://www.opticsplanet.com/truglo-brite-site-tfx-sights-for-glock-20-21-25-28-29-30-31-32-37-40-41-green-re.html
The TruGlo Brite-Site TFX Sights For Glock will not work with Glock MOS models and will not fit Glocks that have a aftermarket slide cut for red dots.
No. These TruGlo Brite-Site TFX Sights will not fit. The correct sights for both of your Glocks can be found using the following link.
https://www.opticsplanet.com/truglo-fiber-optic-s-babbbd.html?_iv_gun-make=glock&_iv_gun-model=glock-21
The rear sight would project too far forward.
That will depend on the optics cut of your slide, for the MOS models this rear sight will not work.
The rear sight in this set projects too far forward.
You can actually do both.
You could do that, depending on how far forward your optics cut on your slide is.
Yes, these are suppressor height tritium and fiber optic night sights. They do not make them in any other color at this time.