MagpulTactile Lock-Plate Mag Enhancement (Pack of 5), Type 1, Black

I got these for safety reasons - mainly to have an additional safety check to prevent 300BO kabooms in .223/5.56 chambers. They work. I will use them exclusively on 300 Blackuot, and use the one-tit for sub-sonic; two-tit for full-power loads. Cheap and useful safety and functional improvement. I don't buy gimmicy tacticool gear - these are legit, useful tools if you have a need for them.