will did you see how it is a circle well that is called an airfoil and that helps stableize the arrow during flight and it is very small which cuts crosswind deflection alot and when you make a passthrew the F.O.B pops off and stays were you shot the animal and can start to track it from there... there that is pretty much it
When you have a pass thru your arrow will probably already be somewhere in the vicinity and there will probably be at least some blood where the animal was standing anyway but I have never never tried these or seen them shot other than on video so I can't say whether they are realy helpfull or not.
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2004 Hoyt Supertec
Trophy Ridge Matrix 5 Pin
Muzzy ZE
Gold Tip Xt Hunter
Slick Trick 125
on passthru it pops off and there is less going thru the animal giving you better penetration if you have any more ? go to archery talk.com and pm paul morris he is F.O.B president