This is an adjustable hand gripper.

This adjustable counting hand gripper offers 5-200kg variable resistance; twist the front knob to adjust tension for beginners, rehab and forearm workouts. The built-in mechanical counter resets via the bottom knob to record reps accurately. Ergonomic non-slip rubber handles fit palms comfortably, while thick elastic stainless steel springs ensure long service life. Compact and portable for home, office or gym use, it boosts finger, wrist and forearm strength and supports post-hand-surgery rehabilitation.