plugs
 

Does anyone know what the purpose of a plug for a Glock is? Obviously to fill the void behind the magazine but why is that there and what would the purpose of plugging it be?

Well, the void is there I think to just fill out the shape of the grip. It could've been made solid, but it's cheaper and easier to make it hollow.

Using the plug has mostly cosmetic benefits, but you can store some very small items in it. I hear of people throwing a spool of fishing line and a couple of hooks and matches in there.

Use your imagination. What would YOU do with it?

There are plugs that are weighted. Most are just aesthetic. The hole actually allows a stuck mag to be stripped out.