Elixir 12077 Nanoweb Electric Guitar Strings, here in Light / Heavy, are coated with a flexible, strong, yet micro-thin polymer tube that prevents contamination and corrosion from collecting in the windings of the nickel plated steel wound strings. With an anti-rust plating on the plain steels too they resisting tone-deadening corrosion. This lets you play for longer and sound better.Elixir's last up to 5 times longer without compromising the bright and crisp tones associated with nickel plated steel. This means you buy fewer sets, change them less often, and trust that your guitar is ready to go when you need it. We use these at Guitarbitz and they are the number 1 coated string!Here in a light / heavy gauge, the thicknesses are 10, 13, 17, 32, 24, 52.