Lens Type: Spherical Lens Spherical Power: -4.25 Dioptres Cylindrical Power: 0.00 Dioptres Axis Power: 0 degree Color: Clear Disposability: Monthly Aquasoft aquasoft HYDRA from Silklens is a contact lens which can be used for a whole day without any problem for the eyes. The lens should give clear and correct vision. Aquasoft Hydra lenses are the ones which have all these qualities and can be used for hours. It does not create any uneasiness or irritation to the eyes. It rectifies the vision over a period of time. You need not worry about changing the lens every now and then.