This is the information I have found from the ABCC Broadhead Master List and "Broadheads 1871 - 1971".
H.C. Stockfleth from Chatham, NJ filed for a patent for the Nybre on January 4, 1954 and was manufactured by Hilbre Archery in 1954. He also patented the Hilbre broadhead.
The Nybre was a molded nylon head with internal spiral threads so they could be screwed on to a standard 5 degree taper shaft, eliminating the need for gluing to shaft.
Interesting package and information. You can even find Bear Razorheads with another companies packaging.