Modern Vintage Baoding Balls/Case

from China in original blue satin brocade box approx 4 5" l x 3.5" w x 2.5" h. Balls are approx 1.5" diameter. Case has small rub spot on top left corner. Balls make soothing musical sound when rotated in palm of hand. Great to inhance flexibility in hands. Original paperwork includes instructions of benefits