Hydro Buoys are color-coded. Minimum (disc size 2" x 5.75") is Green/White, Medium (disc size 3" x 5.75") is Yellow/White and Maximum (disc size 4" x 5.75") is Blue/White. - Soft EVA bells for long wear and comfort. - Buoys act like weighted barbells for conditioning in the water. - Colored cylinders offer easy size selection poolside. - Soft padded hand grip. - Won't chip or absorb water. - Owner's illustrated manual included.