The Martin MM11 Retro Monel acoustic guitar strings, in custom light gauge 11-52, are made from a nickel-based alloy blend to create a quickly mellowing string for vintage tones. These are just like strings used to be back in the day! These strings will bring out unique woody tones from your acoustic that you've not heard before! If you like that old-school, vintage characteristic then these are the strings for you!ÿIn light gauge 11-52 these strings have plenty of balance, powerful bass end with crystal clear high end - great sounding strings. The individual string thicknesses are: 11, 14, 23, 31, 41, 52.