Standard postage cost is £2.99 per order to mainland UK addresses. Cylinders are £10 per cylinder.
Masks let you see underwater by creating an airspace between the water and your eyes. The mask must fit properly to be comfortable and to create a watertight seal. The peripheral vision of a given mask style is determined by its shape and volume,the colour of the silicone and the number of lenses.
The silicone skirt should be soft for your comfort and also provide a good seal. Transparent skirts let in more light but divers who need to focus on individual items ( eg photographers ) may prefer black skirts.