the first batch i got was ones that they didnt put lok tite on the set screws for the blades and i had a problem with the set screws comin out . but i called nap and they sent me 6 heads and 2 practice heads witch was awsome of them to do . (they have great customer service ) . on performance , mine fly great , and ive only shot a doe so far this year and the scene was striaght out of a slasher movie . she ran about 50 yards and was sprayin blood the whole way , ive never saw devastation like it in my life not even from rage heads .