Purchased Arredondo ( pronounced Ar-re-don-do ?) mag extensions for my Glock 20.
Used to use Speer Plus 2 on my mags. These are plus 5!
So my Glock 20, really is a Glock 20 now, plus one in the pipe and one in the butt.
Very pleased with these.
Company does not call them extensions, they call them base pads. They also sell something they call extensions, but they do not increase ammo in the mags.
https://www.arredondoaccessories.com/category.cfm?cid=1001,2015&PID=fc25l4900kouep&GID=gpad