My Grandpa died in 2001, when I was 10. Since then I started collecting knives, and now I'm almost 16, so my Grandma decided to give me his old knives. He only had 2. One, that I have no idea what it is, just an old pocket knife. The other might be a switchblade, possibly a Stiletto. I doubt it is, but there's a feature on the knife that I'm curious about, but I have no idea what it does. I took some pictures so I would like it if you guys could help me out.
This is the part I was curious about, the thing that sticks out on the right. I'm sure you who have been collecting knives for a long time know what it is, but I'll tell you about it anyway. It moves in and out when I open the blade, but I also can move it by pushing it.
Here's 2 picture of the top part of the handle on a side view.
