Hand gripper for grip strength training using four springs. - Brand: Gear - Type: Hand Gripper - Color: Black - Number of Springs: 4 - Application: Grip strength training I used it for bouldering training, but it seems effective for muscle and grip strength training when playing musical instruments or gaming as well. Images 4 and 5 were taken using a smartphone stand, and the smartphone stand is not included in the product. Please understand the above before purchasing.