Used to add weight to machine washable crafts like weighted blankets, weighted lap pads etc.
From the manufacturer:
Poly-Pellets are used in dolls and stuffed animals to provide weight in the base and help them sit upright. They are the perfect material to use in weighted blankets, vests, lap pads, shoulder snakes and other sensory accessories. Poly-Pellets won't mildew or sprout like rice or bean, so they are also perfect to use around the home. You can use them for weighing down drapes, shower curtains and tablecloths, or for draft dodgers and customized door stops. You can use the 6lb bag to make corn hole bags, hacky sacks, stress or sensory balls. They also work great for center pieces and holiday decor, eye mask and phone or camera rests. Now with a convenient "Easy Pour and Store" spout in a stand-up bag.