International System of Units explained simply. How Equipment Works Second Definition, Tools, Conversion Chart, Uses Convert Seconds to Hours Instantly Simple Steps & Examples TIL the most accurate measurement definition of a second is the number. The Second Skin collection is designed to feel like an extension of your own skin. These slips are expertly designed to reduce transparency beneath sheer clothing, with a fluid, lightweight fabric that ensures comfort and easy maintenance. Available in sleeveless and full sleeve styles, along with tops and leggings, this range offers complete coverage for confidence and peace of mind. Select from seven shades.