Lotus Connect Store › EISCO Specific Gravity Cubes with Hooks (Set of 4) EISCO Specific Gravity Cubes with Hooks (Set of 4) $17.45 Brass, iron, aluminum and zinc 20mm cubesHooksThis density cube set containts the follow metal cubes: brass, iron, aluminum and zinc. They are .79in (20mm) cubes. Quantity: Add To Cart Added! Brass, iron, aluminum and zinc 20mm cubesHooksThis density cube set containts the follow metal cubes: brass, iron, aluminum and zinc. They are .79in (20mm) cubes.