LIRS stands for Large Iron Retention System. This vise is made for tying big flies on big hooks. The jaws of this vise are setup to grip the hook in a different way then most vises (you pass the hook through a channel that you then tighten down on the hook instead of jaws grabbing it on either side. Has rotary capability and a nice heavy pedestal base which allows you to tie anywhere. Available new in box or as a slightly used shop vice (to save you some bucks).