... disc , pvc balance disc , balance board , twist board ,seat cushion ,massage mat2.material: phthalate free pvc (soft & hard )3.dia: 33cm or 61cm4.color ... provide "CE" and 'ROHS" certification11.it is used to exercise balance or massage , especiallly suit for yoga exercieser usage: 1. ... the floor , then stand on the smooth side --- exercise balance 2. seat on the spikes--massage. massage balance disc