Koro was asked to make the Aldrich grizzly bear throw spring a couple years ago. Koro has developed a name for making great springs and we feel that we did well on the Aldrich throw spring. This spring is made very similar to the best known original. The Koro throw spring is made of .283 dia. Music wire that is made in house. The Koro throw spring can be used on grizzly or black bears.