SHHHHH. That is the top secret modification magazine catch tighter upper. When the Army CID and the FBI come around we will tell them that your computer had been hacked by Russianicon agents trying to influence the 2018 elections. And if they don't believe it we will tell them your computer was playing....Russian poker music and it was in the National Inquirer so it must be true right????

But I can see how it would work if needed to made the catch tighter to hold a magazine.