The AKG ck91 cardioid caps come with the 300 bodies when bought new. If you are buying used and have a choice, I would go with the ck93 hyper caps. I found them to sound smoother and without a lot of the lower end balloon of the ck91 caps. They also did a very effective job of reducing crowd noise. I really, really liked the ck93 hyper caps, but I do almost all of my recordings indoors in poor-sounding places. If you do a lot of outdoor shows, you may want to check out the ck91s if you have a choice of caps.