What is the advantages of it ?

It helps line up your shot so you won't be too far left or right.

For instinctive wing shooting I'm not sure if they add much (but certainly aren’t' hurting anything either). However, if you hunt Turkeys they are a valuable "rear site" (both windage and elevation)

I'm sure someone more educated on this will come along and be able to provide more.

best o luck

Nate

The double bead system is really for mounting your gun in the same position every time. When the gun is mounted you should see a figure eight when looking down the barrell. This allows you to know if the gun is mounted properly and you head position is the same every shot. Most competition guns have twin beads. Also remember you should never use your beads as sights when shooting clays they are for reference only.

Have fun

The double bead system is really for mounting your gun in the same position every time. When the gun is mounted you should see a figure eight when looking down the barrell. This allows you to know if the gun is mounted properly and you head position is the same every shot....
Have fun
X2

That is prolly the best laymen's description I could ever hear!

You nailed it mauser!