Polyurethane foam;These fun building block stress balls are a great way to promote team unity and skill building in the workplace Our handcrafted polyurethane foam stress balls are a fun way to promote your company organization hospital or school while also helping everyone who receives one squeeze away the stress of everyday life!; NOTE: Due to their handcrafted nature stress ball sizes colors and textures may vary Factory cannot guarantee consistent imprints or PMS matches; Not intended as a child's or pet's toy; NOTE: while pieces do stack like traditional building blocks they are sold individually and not as a set; Product Size: 3.125" w x 1" h x 1.5" d;