If you're in to olympic lifting or powerlifting, you'll know that a strong grip is important in controlling the bar, and ultimately making the lift. If you're deadlifting consistently, then your grip strength will eventually begin to lag behind your lifts. Straps and hooks can prevent you from dropping the bar on your heaviest set, but won't increase your grip strength.
Grippers are an affordable, compact and very effective tool in improving your grip strength. Whatsmore you can use them almost anywhere, sitting at a desk, on the couch or anywhere else outside of your regular training sessions.
This gripper is 300lb, a good weight for someone of about 115kg bodyweight or above to start with.