I have realized that a Hex Bar (also known as a Trap Bar) has been one of the best pieces of equipment for BJJ.
Not only can I work squats and deadlifts with this bar to build core and leg strength, but I can combine it with grip training for BJJ.
The versatility of this piece of equipment is limitless and if you add a BJJ gi to the mix, then you have a whole other variance of exercises that are both effective and BJJ-specific. Check out these exercises and try them out for yourself.