
Two products carry the Avaira Vitality name here, both sold in six packs: the standard lens and the toric version. Which one you order is not really a preference, it is written on your prescription.
A contact lens prescription is more specific than a glasses prescription. Alongside the power for each eye it names a base curve and a diameter, and for a toric lens it adds a cylinder value and an axis in degrees. All of those numbers belong to the exact lens you were fitted in. They do not transfer between brands, and a toric prescription cannot be filled with a spherical lens.
Check the right and left lines separately, because the two eyes are frequently different and one may need a toric lens while the other does not. Then decide quantity from your wearing schedule and how far ahead you want to buy. Six packs are the common unit, and buying several at once means fewer reorders.
Moving between the sphere and the toric version is a change your prescriber makes at a fitting, not one to make at checkout.
Contact lenses are prescription products in the United States. You will need a current prescription from your eye doctor, and if it has lapsed, an appointment comes before the reorder.