This is a 100-round magazine for 5.56 x 45 mm ammunition.
You do not need that. No one outside of an infantry engagement needs that.
That is all.*
*Cue gun fetishists telling me that I don’t know what I’m talking about, others accusing me of wanting the eeevil gub’mint to enslave us all, others saying that I’m a traitor to the Constitution, and still others rationalizing that this maniac would have murdered a dozen people with Matchbox cars if he hadn’t had 100 rounds of .223 Remington ammo at his disposal. Yes, I’ve been down this road before.