Total Size : 48 x 38 x 41mm / 1.9" x 1.5" x 1.6" (L*W*H) Hole Dia. : 4mm /0.16";Roller Size : 31 x 15mm /1.2" x 0.6" (D*T) [Material] - The caster wheel is made of plastic, it rolls smoothly and quietly [Features] - Elasticity, toughness and durability.