Grip Strength Trainer, Hausbell Hand Grip,30-145 Lbs Hand Grip Fitness Adjustable Hand Strengthener Resistance Strength Trainer Non-Slip Gripper (6 Pack) 1. Automatic human sensitivity: The light will be lighted when some body comes, and the light will be turned off when he leaves. 2. Easy installation, safety and energy saving. The rate of electricity is more than 85% 3. Electronic switch is applied and it will not cause electricity spark and interfere the other electric appliance 4. Strong anti-interference, low power-wear and long using life. 5. Intellective time-delay. The service load will keep working when some body moves about in the detecting area