What to look for in a bolt in sprag?

So Im upgrading my trans for by BB car while its out and putting a bolt in sprag in. I noticed Summit sells TCI's for $75, CRT has what looks like their house version for $105, and the variations continue up to about $130 before they jump to $190. So any experience with the TCI or the CRT one? Or what should I look for when buying one? FYI, I know almost 0 about trannys (for cars :D) Thanks!