Features: 1)These lycra covered gel squeeze balls are proven means of reducing stress. When squeezed, these squeeze balls reduce muscular tension and reduce stress, Stress release 2)Can imprint the logo on the lycra cloth, suitable for the promotional gift 3) To be designed to increase hand strength and flexibility 4) Squeezable, hi-bounce Pickleballs are hollow plastic balls with holes. Balls are categorized as either indoor or outdoor. Indoor pickleballs typically have larger holes since wind isn't as much a factor. Outdoor pickleballs are made of a harder plastic for durability on harder surfaces, and have smaller holes.