These clear balls are made of pure acrylic plastic. Machined and polished free of internal distortions or scratches. Zeekio acrylic balls are tough, chip resistant and almost completely shatterproof. 100% Acrylic Plastic ( made from 100% recycled material) No bubbles or inclusions Made in China All clear acrylic balls are perfectly round without surface scratches or blemishes. Clear acrylic balls can magnify sunlight, so you have to be sure not to leave them out in direct sunlight, or even sunlight coming though a window. A colored ball acrylic ball will not do this as much, depending on how dark the ball color is. 100mm - approx. 4 in. / 654g