I highly reccomend ANY NAP product. I have been using their expandibles
(100gr Shockwaves) for years. The Spitfires are the TOP shelp of expandibles, no rubber "O" ring. The blades are held by a ball detent, and sometimes Chad, these heads will be found closed after you , the hunter, knows he had a pass thru. Check out the wound, if in doubt of the head opening and you'll see it expanded quite nicely.
Go get P&Y 12 with them will ya?