I didn't think of it at the time, but the Wasp Jakhammer is another good one to consider, if you like that particular style of broadhead. They do use an O-Ring for retention. Some might consider that old-fashioned, but they way they use it is foolproof and reliable. The other thing you should know about Jakhammers is that they use a stainless trocar tip that's harder than hammered hell and they also use blades that are noticeably thicker than the other brands. Spitfires and Grim Reapers are good broadheads, but the Wasp is another serious contender in that category, and often overlooked.