You can do a seach and find some discussion on these. I shot a muley doe last year at 43 yards, blew right through and seemed to perform as expected. HOWEVER, since that time I am now unsure as if they are legal.
The rear of the razor wire is not 100% fixed. It is designed to have some give to it. However, it is fully closed at the rear.
The flew true and did the job.
FYI, if you get them do not test them by running your finger over the surface quickly, you will need some stitches to close it up.