RGP (Rigid Gas Permeable) Lenses
Rigid gas permeable contact lenses take longer to adapt to, but are more durable and more resistant to deposit buildup. They tend to be less expensive over the life of the lens (but the upfront cost is higher) and can offer some people crisper vision than they would have with soft contacts. With GP lenses, you generally replace them every couple of years, because they are made of a very durable material (though a prescription change would necessitate new lenses).