I like the author's last name:
Brownells’ AR-15 .22 LR Conversion Kit: "Ammo prices being what they are these days, I find myself looking into .22 LR conversion kits for guns I like to shoot regularly. Currently, my preferred load for AR-15s is running just over $0.40 per round, while .22 LR is running about $0.03 per round. So I was obviously interested in Brownells’ AR-15 .22 LR Conversion Kit. I reasoned that, after one 550-round milk carton of .22 LR, the $199 kit would pay for itself. The other option would be a dedicated .22 LR upper, which costs more and I’d have to purchase additional optics and other accessories to make it comparable to my other AR-15s. The kit seemed like a no-brainer, presuming it worked."