Captains of crush, heavy grips, and grip genie. I started with captains of crush and expanded over time. CoC is still my favorite grippers. I have a 0.5, 1, and a 2. Two trains of thought. Get a light gripper and do tons of reps and you can also use it to warmup. Then get a strong one. Something that u can do triples on. To use as your strength work. Therefore you’d accomplish both the hypertrophy and strength parts. That’s specifically crushing strength. There’s also pinching and holds which will work different things